Same body, same 108-inch wheelbase, same four-speed automatic, three very different personalities. The Buick Grand National, the Chevrolet Monte Carlo SS and the Oldsmobile Cutlass Supreme 442 are the three G-body coupes everybody lumps together, and for good reason: in July 1985 Car and Driver lined them up and noted they share a body shell, transmission, suspensions, brakes, tires and front-seat frames. What separates them is the engine, the nose and the attitude. Here is the short version with the numbers first, then the long version.
Key Takeaways
- Quickest: Grand National. Its turbo 3.8 V6 makes 245 hp and 355 lb-ft in 1987 trim, far more torque than either V8.
- Best all-rounder: Monte Carlo SS. Car and Driver’s 1985 favorite, the most built (about 161,000) and the easiest to buy and upgrade.
- Rarest: Cutlass 442, about 11,481 built, with the stoutest factory axle of the V8 pair (8.5-inch, 3.73 gears).
- Shared: G-body chassis, 108-inch wheelbase, 200-4R four-speed automatic, front disc/rear drum brakes. No manuals.
The specs, side by side
| Buick Grand National | Chevy Monte Carlo SS | Olds Cutlass 442 | |
|---|---|---|---|
| Years | 1984 to 1987 | 1983 to 1988 | 1985 to 1987 |
| Engine | 3.8L (231 ci) turbo V6, sequential fuel injection | 5.0L (305 ci) H.O. V8, Quadrajet 4-bbl | 5.0L (307 ci) Olds V8, Quadrajet 4-bbl |
| Engine code (RPO / VIN 8th digit) | LM9 / 9 (1984-85); LC2 / 7 (1986-87) | L69 / 7 (1983); L69 / G (1984-88) | LG8 / 9 |
| Horsepower | 200 (1984-85); 235 (1986); 245 (1987) | 175 (1983); 180 (1984-88) | 180 (early 1985); 170 (late 1985-87) |
| Torque, lb-ft | 300 (1984-85); 330 (1986); 355 (1987) | 230 (1983); 225 (1984-88) | 240 (early 1985); 250 (late 1985-87) |
| 0-60 mph | 7.5 sec (1985, C/D); 4.9 sec (1987, C/D); 6.0 sec (1987, R&T) | 7.8 sec (1985, C/D); 8.2 sec (1983, C/D) | 9.1 sec (1985, C/D) |
| Quarter mile | 15.7 @ 87 (1985, C/D); 13.9 @ 98 (1987, C/D); 14.7 @ 94 (1987, R&T) | 15.9 @ 86 (1985, C/D); 16.1 @ 88 (1983, C/D) | 16.6 @ 83 (1985, C/D) |
| Weight | 3,460 lb as tested (1985, C/D); 3,380 lb shipping (1987) | 3,530 lb as tested (1985, C/D) | 3,570 lb as tested (1985, C/D) |
| Transmission | THM 200-4R 4-speed auto | THM 350C 3-speed (1983-84); 200-4R (1985-88) | THM 200-4R 4-speed auto |
| Rear axle / ratio | 8.5-in 10-bolt (1986-87), 3.42:1 | 7.5-in 10-bolt; 3.42:1 (1983-84), 3.73:1 (1985-88) | 8.5-in 10-bolt, 3.73:1 |
| Production | 2,000 / 2,102 / 5,512 / 20,193 (about 29,800) | 4,714 / 24,050 / 35,484 / 41,364 / 39,251 / 16,204 (about 161,000, incl. 6,252 Aerocoupes) | 3,000 / 4,273 / 4,208 (about 11,481) |
| Look for | Stock, documented car; WE2 on trunk label; exhaust manifold leaks, turbo oil lines, Powermaster brakes, rust | Correct VIN code, real Aerocoupe RPO, rust at rear glass and quarters, 7.5-in axle wear | Matching 307 and original 3.73 axle, two-tone paint and trim, rear frame rust |
A few notes so the table doesn’t lie to you. Horsepower and torque are factory SAE net ratings. The only clean three-way acceleration test is Car and Driver’s July 1985 comparison, run on 1985 cars, so the Grand National in that test is the 200 hp non-intercooled car, not the 245 hp 1987. Car and Driver later ran a 1987 GN to 60 in 4.9 seconds with a 13.9-second quarter at 98 mph, while Road and Track got 6.0 seconds and 14.7 at 94 mph out of theirs. Same model, different car, different day. Treat any single 0 to 60 number as a snapshot, not gospel.
One platform, three divisions
GM’s rear-drive A-body was renamed the G-body for 1982, when the front-drive A-body Celebrity, Century and Cutlass Ciera took the A letter. Underneath, these cars are pure old-school GM: a full perimeter frame, unequal-length control arms up front, a four-link coil-sprung live axle out back, 10.5-inch vented front discs and 9.5-inch rear drums. Every car here got the THM 200-4R four-speed overdrive automatic (the 1983 Monte SS and nearly all 1984s used the three-speed THM 350C). There was no manual. Car and Driver grumbled about that in 1985, and so do I.
What each division got to play with was springs, shocks, sway bars, bushings, steering ratio, torque converter, axle, engine and sheetmetal from the cowl forward. That is why the three drive differently even though the seats, the switchgear and the view out the windshield are near identical.
The good news for owners today: because GM built millions of G-bodies (Regal, Cutlass Supreme, Monte Carlo, Grand Prix, El Camino and more), suspension, brake and body parts are cheap and plentiful, and the aftermarket treats the G-body as a first-class platform.
Buick Grand National (1984 to 1987)
I’ll admit my bias up front. I love Buicks, and the GN is the Buick that made the Corvette crowd nervous. It is also proof of something I’ve believed since I started turning wrenches on my ’87 Subaru: a V6 with the right breathing beats a lazy V8.
The engine. The 3.8-liter (231 cubic inch) Buick V6 is a 90-degree pushrod engine with sequential port fuel injection, distributorless ignition and a Garrett turbocharger. In 1984 and 1985 it ran without an intercooler and was rated 200 hp and 300 lb-ft (VIN engine code 9, LM9). For 1986 Buick added an air-to-air intercooler (VIN code 7, LC2) and rated it at 235 hp and 330 lb-ft. For 1987 the rating climbed to 245 hp and 355 lb-ft. Buick engineers later admitted the ratings were a game of staying a step ahead of Chevrolet’s V8s, and most owners believe even 245 was modest.
The drivetrain. THM 200-4R with a 3.42:1 axle. The 1986 and 1987 cars use the 8.5-inch 10-bolt; limited slip (G80) was optional until it became part of the required equipment on late 1987 builds. I could not confirm the axle size on 1984 and 1985 cars from a source I trust, so check the axle code on any early car before you assume it has the 8.5.
The look. All black, all business: black paint, black bumpers and trim, a black grille, a rear spoiler and the hood bulge that clears the turbo plumbing. Chrome-faced aluminum wheels are about the only bright pieces. The 1987 grille is all black with no flat top surface, which is one quick way to tell it from a 1986.
Production. About 2,000 in 1984, 2,102 in 1985, 5,512 in 1986 and 20,193 in 1987. The 547 GNX cars are counted separately, and they are another conversation (and another price bracket) entirely.
What goes wrong. Most problems trace back to heat and age. Check for a leaking or cracked driver-side exhaust manifold, tired turbo oil feed and return lines, a stretched timing chain, brittle intercooler and vacuum hoses, and 1986 and 1987 Powermaster brake systems that work only as well as their pump and accumulator. Look for rust in the rockers, A-pillars, drip rails, floors and T-top surrounds. Modified cars are everywhere; a stock, documented car is worth much more than a car with a big chip and a mystery history.
Chevrolet Monte Carlo SS (1983 to 1988)
The Monte SS is the NASCAR car you could buy at the Chevy store, and it looks the part. It was Car and Driver’s overall favorite in 1985, because it balanced acceleration, braking and handling better than the Buick, even if it couldn’t keep up with the GN in a straight line.
The engine. The L69 5.0-liter (305 cubic inch) H.O. V8 with a Rochester Quadrajet four-barrel was the only SS engine. Chevy rated it 175 hp and 230 lb-ft for 1983 (VIN code 7), then 180 hp and 225 lb-ft for 1984 through 1988 (VIN code G). Car and Driver described it as a 9.5:1 compression small-block with a hotter cam, essentially the carbureted Z28 engine. It is a good engine, and if you have read my rants, you know I think its big brother, the 350, is the best engine GM ever built. The 305 in the SS is the sensible version of that idea.
The drivetrain. The 1983 and almost all 1984 SS cars used the three-speed THM 350C with a 3.42:1 axle. From 1985 the SS got the 200-4R and a 3.73:1 axle. The weak link is the 7.5-inch 10-bolt; it is fine with stock power but it is the first thing to break when the motor gets help. Decode yours with our GM rear axle code decoder.
The look. The SS gets the smooth, sloped aero nose with a body-color fascia, a rear spoiler and SS striping. For 1986 and 1987 Chevy built the Aerocoupe for NASCAR homologation, with a steeply raked, bubble-style rear glass and a short decklid: 200 in 1986 (all white with burgundy interior) and 6,052 in 1987. Beware: a real Aerocoupe is worth a premium, so verify the RPO code (B5T for 1986, Z16 for 1987) on the service parts sticker rather than trusting the glass.
Production. 4,714 (1983), 24,050 (1984), 35,484 (1985), 41,164 plus 200 Aerocoupes (1986), 33,199 plus 6,052 Aerocoupes (1987) and 16,204 (1988). That is roughly 161,000 fourth-generation SS cars, which is why the Monte is the easiest of the three to find and buy.
What goes wrong. Rust around the rear window and lower quarters, leaky T-tops, sagging doors (here is how to fix sagging GM doors with new hinge pins and bushings), cracked dashes, a tired Quadrajet (our Quadrajet number decoder will tell you if the carb is even original) and a worn 7.5-inch axle.
Oldsmobile Cutlass Supreme 442 (1985 to 1987)
The 442 is the quiet one. In 1985 Car and Driver said that apart from the wheels, tires and decals, it could be any other Cutlass, and they meant it as both a knock and a compliment. Today that understatement is part of the appeal, and it was the slowest of the three in that test.
The engine. The 442 used the Oldsmobile 5.0-liter (307 cubic inch) four-barrel V8, the LG8 (VIN code 9), which it shared only with the 1983 and 1984 Hurst/Olds. Early 1985 engines were flat-tappet and rated 180 hp and 240 lb-ft. Midway through 1985 Olds switched to roller lifters and new swirl-port heads, and the 1986 and 1987 cars were rated 170 hp at 4,000 rpm and 250 lb-ft at 2,600 rpm. (Some references list 255 lb-ft; Oldsmobile’s own 1987 catalog says 250.)
The drivetrain. The 200-4R and, here is the big one, the 8.5-inch 10-bolt with 3.73:1 gears, the same stout axle family the Grand National used. Many 442s left the factory without limited slip because G80 was not part of the popular option packages. That axle is so desirable that it gets pulled out of 442s for other projects, so make sure the one under your car is the one it came with.
The look. The 442 wears the Cutlass Supreme coupe body and front end with a two-tone paint scheme, a contrasting lower body with 442 striping and badges, gold-accented 15-inch wheels and Goodyear Eagle GT tires. Pretty, not mean.
Production. 3,000 in 1985, 4,273 in 1986 and 4,208 in 1987, about 11,481 in all, which makes the 442 the rarest of the three by a mile.
What goes wrong. The usual G-body frame rust at the rear control arm mounts and rear frame rails, a tired Quadrajet, worn suspension bushings and missing 442-specific trim, which can be hard to find. A 442 with matching drivetrain, original two-tone paint and its 3.73 axle intact is the one to buy.
Can you clone a Grand National from a Cutlass 442?
People do it all the time, and the 442 is actually the best starting point because it already has the 8.5-inch axle with 3.73 gears and the 200-4R. A Regal coupe is the easiest donor of all, since the body is already a Regal. Here is what’s involved.
Body. The Regal and Cutlass Supreme coupes share the main body shell, doors and glass. What differs is the division-specific sheetmetal and trim, starting with the front end: fenders, header panel, grille, hood and front bumper. The rear bumper and taillight treatment are also different. To make a Cutlass look like a GN you need the Regal front clip, the GN hood with its bulge, the GN bumpers, grille, spoiler and trim, the black paint and the interior pieces. That shopping list adds up fast, and good GN-specific parts are not cheap.
A real turbo V6. Swapping in a 3.8 SFI turbo means more than the engine. Plan on the turbo and intercooler, the GN wiring harness and ECM (or an aftermarket EFI system), a high-pressure in-tank fuel pump with a return line, the correct injectors and MAF or speed-density setup, exhaust, a radiator up to the job, and the trans calibration. The Buick V6 shares the BOP bellhousing pattern with the Olds V8, so the 200-4R bolts up, but a stock 442 converter and valve body are not set up for turbo torque. Many builders swap in a built 200-4R, or a 4L60E with a standalone controller. The 8.5-inch 10-bolt is fine for a mild turbo car and needs help when you turn the boost up. Call it an advanced project: weeks of wiring and plumbing, not a weekend.
An LS instead. If you want GN looks and modern reliability, an LS swap into a G-body is well supported, with off-the-shelf engine mounts, headers, oil pans and wiring. It will make more power for less money than a period-correct turbo build. It also won’t make any turbo noises, which matters if the whistle is why you wanted a GN in the first place. Personally, I’d do the turbo V6. I find 60-degree V6s the most fun to modify, but the 90-degree Buick turbo engine earns a special exception.
Value and honesty. A clone is never a real Grand National, and it will never be worth what a real one is. A real 1986 or 1987 GN has a 7 as the eighth VIN digit and WE2 on the trunk-lid service parts label. Even those can be faked, so serious buyers also check body and cowl tags and the paperwork. If you build a clone, call it a clone in every ad, on every title and to every buyer. Selling a clone as a real GN is fraud. Build it because you want to drive it, and you’ll be happy.
Can a 442 run with a GN?
Stock against stock, no, and it isn’t close. The 1987 Grand National is rated 245 hp and 355 lb-ft. The 1986-87 442 is rated 170 hp and 250 lb-ft. Car and Driver’s 1985 442 went 0 to 60 in 9.1 seconds and ran a 16.6. Their 1987 GN did it in 4.9 and ran a 13.9 Even Road and Track’s slower GN (6.0, 14.7) would have the Olds covered.
Why not just build the 307? It’s smooth and durable, but it was built for economy: small ports, a small bore, low compression and almost no aftermarket. Money spent on a 307 goes further on a bigger engine.
To match or beat a GN, figure you need roughly 300 hp or more at the wheels for low-13 to high-12 second quarter-mile times. Every number below is my estimate, assuming you do the work yourself.
A built Olds V8 (350, 403 or 455). Plan on roughly 350 to 420 hp at the crank from a built 350 or 403, or more from a 455, which bolts in with the same BOP bellhousing. You’ll want a 2,500 to 3,000 rpm converter, a built 200-4R or a TH350/TH400, and traction help. Keep the 442’s 3.73 gears. They suit a V8 better than the GN’s 3.42. Rough cost: $5,000 to $12,000.
A Buick 3.8 turbo swap. A healthy turbo 3.8 with a chip, a bigger intercooler and fuel upgrades can make roughly 300 to 350 wheel hp. All the supporting parts from the clone section apply. A converter in the 2,800 to 3,200 rpm range helps spool, and the 3.42 to 3.73 range works fine. At that level the 200-4R needs a rebuild, and the 8.5-inch 10-bolt needs at least a limited slip and good axles. Rough cost: $8,000 to $20,000 or more, depending on how complete your donor is.
An LS swap. A junkyard 5.3 with a cam and a tune can make roughly 330 to 380 crank hp. Pair it with a 4L60E or 4L80E, a 2,800 to 3,200 rpm converter and 3.42 or 3.73 gears. Rough cost: $4,000 to $10,000. It’s the cheapest way to a GN-fast 442.
Whichever path you pick, the 8.5-inch axle becomes the weak link somewhere around 400 wheel hp on sticky tires, and a good drag radial will do more for your ET than another 30 horsepower.
A full build walkthrough is coming soon.
Which one should you buy?
Buy the Grand National if you want the fastest car, the strongest collector market and the one everybody at the gas station wants to talk about. Hagerty’s July 2025 guide put a 1987 at about $65,100 in #2 (excellent) condition and $37,300 in #3 (good) condition. Buy the most original, best documented car you can afford, and have a turbo Buick specialist look it over.
Buy the Monte Carlo SS if you want the best all-around driver, the biggest parts supply and an easy small-block Chevy upgrade path. It is also the least expensive way into a G-body with a factory performance badge. Hagerty listed a 1987 SS at about $21,500 in #3 condition in early 2026. Aerocoupes and 1983 cars carry a premium.
Buy the 442 if you like being the only one at the show. It is the rarest, it has the best factory axle of the V8 cars, and it is the best clone base if you ever get the turbo itch. Hagerty listed a 1986 at about $17,700 in #3 condition. Collector values move, so check the current numbers before you write a check.
My pick? You know I’m a Buick guy. But if I only had one garage spot and one budget, I’d buy a clean, honest Monte SS, drive the wheels off it, and save for a GN.
For more classic GM projects, see how to replace upper control arm bushings on a GM A-body and how to replace rear drum brake shoes on a classic GM A-body. The same basic jobs apply to a G-body.
Sources
- Car and Driver, July 1985 comparison: Regal Grand National vs Monte Carlo SS vs Olds 442
- Car and Driver, 1987 Buick GNX test (with 1987 GN results)
- Road and Track, 1987 GNX first look (R&T GN test figures)
- Old Cars Weekly, 1987 Buick Grand National
- Hemmings, Buyer’s guide: Buick Grand National
- Hot Rod, What is a Buick Regal Grand National
- GNTType.org, Turbo Regal VIN guide
- Hagerty, Buick turbo buyer’s guide
- Car and Driver, 1983 Monte Carlo SS archive test
- MonteCarloSS.com FAQ: engine
- MonteCarloSS.com FAQ: production
- Hagerty, 1983-88 Monte Carlo SS buyer’s guide
- Hemmings, 1985-87 Oldsmobile 4-4-2
- Wikipedia, Oldsmobile 442 (G-body section)
- Hagerty valuation tools: 1986 Cutlass 4-4-2
Photo credits (Wikimedia Commons): 1987 Buick Grand National by MeanBuicks, public domain. 1986 Chevrolet Monte Carlo SS by Elise240SX, CC BY-SA 4.0. 1987 Olds Cutlass Supreme 442 by Gr678537, CC BY-SA 4.0. Photos cropped, combined and labeled by CarNutChronicles; the composite graphic is shared under CC BY-SA 4.0.
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