Disadvantages
A V-6 was the standard engine for the entire run. The Oldsmobile 350 diesel-equipped Grand Prix of 1981-1985 was a poor performer. Don't buy one unless you're planning an immediate engine swap or want to take advantage of the Olds diesel's super-thick cylinder walls to build a big-inch Olds gasoline engine. In 1980 and for 1981, the 265 Pontiac 2V engine became standard in the LJ; just when you thought Pontiac couldn't build a V-8 with less power, here was one with 120 hp. So don't assume a 301 is under the hood of your prospective '80-'81 purchase. It might be in an '80 since both were offered, but in 1981 the only Pontiac engine was the 265. No V-8 gasoline engine was available in 1982.
Standard wheel size was once again 14 inches, down from 15. Rear-gear ratios ran as low as 2.29:1 and many were 2.41:1 or 2.73:1, so a gear swap is necessary if more performance is desired-unless you plan to run at the Salt Flats.
Swapability
You can easily install a '70-up traditional Pontiac engine in the A-special (A/G hybrid) '78-'81 models and do the same using a B-O-P-pattern, bellhousing-equipped, Turbo 350 transmission and '78-'81 Pontiac motor mounts in any '82-'87 G-body (check local emissions laws, however). The 12.7:1 steering box from a Buick GN-/T-Type, Olds 442/Hurst, Chevy Monte Carlo SS, or the '86 Pontiac 2+2 Grand Prix is a direct bolt-in to the G-body Grand Prix, as are their 1.25-inch front and 0.875-inch rear stabilizer bars. Traditional 15x7 Rally wheels are also a direct bolt-on. Other suspension upgrades are possible with abundant aftermarket choices or stock high-performance components from the GN, SS, 442, or 2+2. A 7.5-inch GM 10-bolt was standard, so you can install a Posi unit from any similar-vintage S-series GM pickup truck or swap the whole rear from a 442 or SS. The 8.5-inch rear assembly in the '86-'87 (at least) Grand National and T-Type Buick is a nicer upgrade.
Cool Factor: B
These GPs contain miles of style and an upscale look that was lacking in competing A-special and G-bodies of the era.
Where to Look
Collector Car Trader Online (www.collectorcartraderonline.com).
The following are some examples we found:
'78 Grand Prix, 80,000 miles
Seller's Description: "'78 Pontiac Grand Prix, V-8, auto, cold A/C, 80K actual miles, one owner, mint condition, reduced to $3,950 obo."
'85 Grand Prix, 98,000 miles
"'85 Pontiac Grand Prix LE, 305 V-8, A/T w/overdrive, floor shifter, dual exhaust, power antenna, bucket seats, trunk, and sunroof, rare factory wheels, new paint, 98K miles, very rare car, $2, 900 or best offer."

We know it's a Grand Am . . . we didn't have a good LeMans photo.
The Hook
This two-door coupe screams '70s Colonnade style without a premium price. The '73-'77 LeMans, LeMans Sport, Luxury LeMans, and Grand LeMans all share the same platform with the too-pricey-and-collectible-for-this-story GTO, Grand Am, and Can-Am. They all handle better than similarly equipped '64-'72 models.
Advantages
The LeMans was the base-level A-body from '73 to '77 and was available with a 2V 301 ('77), both 2V and 4V 350, and 400 Pontiac engines depending upon year. The Olds 350 and 403 engines were bolted to California-bound examples in 1977. Though they have less performance than earlier models, these engines respond well to basic upgrades. Many '74 and later models were optioned with RTS (Radial Tuned Suspension) and Rally II wheels, so they handle well for their size. Most feature power steering, power brakes, and A/C because they were designed first as family coupes.
Low-mile examples are available and inexpensive, and one-owner cars can still be had. If you see one advertised as "Mom's LeMans," you can be sure it was never raced, abused, or beaten.
Disadvantages
These vintage, mid-'70s A-bodies aren't as popular as the earlier models. Their design and added safety equipment increase their weight, so performance and economy suffer in stock form. Low compression and highway gears don't help. The good news is, all this can be changed with head, cam, and rearend gear swaps, and upgraded exhaust systems. There are 231ci V-6 examples out there, but they're too heavy to make good use of such a small engine.
Swapability
Most drivetrain components interchange freely between '73-'77 A-/G-body Pontiacs and, for suspension, with all of GM's A-body cousins. The '70-up 400-455 Pontiac engines are direct bolt-ins. Factory four-barrel intakes and Q-jets from '72 to '79 are easy replacements for two-barrel-equipped A-bodies.