In the 1980s, Americans were forced into uncharted waters when it came to cars. They had grown up being told that a car was supposed to have 8 cylinders driving the rear wheels. Now all of a sudden they had to make do with 6 or even 4 cylinders driving the front wheels. The car company that took this change to the max was Chrysler under CEO Lee Iaccoca. By 1990, with the end of the Plymouth Gran Fury/Dodge Diplomat, the company did not offer a single car with rear wheel drive or more than 6 cylinders (besides the Viper). Ford and GM persisted in pushing several rear drive v8 models. I'm going to change that.
Chevrolet Caprice:
GM began the downsizing wave in 1977 when it shrank its bread and butter full sized cars. The platform was used until 1996 with only a reskinning in 1991. This was probably because police departments appreciated the easy repairs afforded by the body on frame construction, but they can learn to adapt. Conveniently, GM did move the full size cars of Buick, Oldsmobile, Pontiac, and some Cadillacs to the smaller front drive H and C platforms in 1986 and it seems pretty simple to build an H body Chevy. This car would probably use, like the other H and C body cars, Buick's 3.8 Liter V6, although it would be neat if they chose to use Oldsmobile's powerful Quad 4.
Cadillac Brougham:
Cadillac had a comically confusing lineup of sedans in the 80s. There was the midsized front drive Seville. There were 3 front drive full size cars: Fleetwood, De Ville, and 60 special. The Brougham was their only rear drive model starting in 1985 and killing it shouldn't be a big problem.
Chevrolet Camaro/ Pontiac Firebird:
It was planned already to replace these two pony cars with front drive sport coupes and we can do that here, no matter how much enthusiasts may whine. This car would probably use Oldsmobile's Quad 4.
Chevrolet Corvette:
The Corvette's status as a serious performance car means front wheel drive is out of the question. The V8 engine is not so sacred however. Its competitors, such as the Porsche 911 and Acura NSX, did with 6 cylinders. Maybe a "Quad 6" could work.
Ford Crown Victoria/Mercury Grand Marquis:
Ford's only full sized front drive platform, anywhere, even including European and Australian subsidiaries, and Mazda, was the stretched Taurus/Sable platform used for the Lincoln Continental starting in 1988. Slapping Ford and Mercury badges on that shouldn't be too hard. This car would probably use Ford Essex 3.8 Liter V6.
Lincoln Town Car:
As I said before, Lincoln had a front drive full size model with the Continental, so the Town Car can be thrown in the ashbin of history.
Ford Mustang:
I'm going to be extra cruel, and use Ford's actual plan to move the Mustang nameplate to the front drive coupe that IOTL was renamed Probe at the last minute. The engines would be the same as OTL Probe: a 2.2L Mazda 4 cylinder in turbo and non turbo versions and Ford's 3.0L Vulcan V6.
Lincoln Mark 7:
Cadillac had been selling the Eldorado with front wheel drive since its inception in 1966, so Lincoln should be able to make a front drive version of their Mark series, perhaps using the Continental platform. As such it would use Ford's 3.8 Liter Essex V6.

Ford Thunderbird/Mercury Cougar:
See Above
So, with that, by 1990, the only rear drive V8 car sold by any of the Big 3 automakers will be the Corvette.