I don't remember which one my 89 3.8 Cougar had, but the replacement AOD from a V8 mustang was the other one. The tranny shop tried to get it right (pacing the car with a truck with 4 different sized tires, rags stuffed into the fuel fillers, among other rednecky stuff) but I eventually took it to a speedometer shop with a syno to get it right.
Obviously there is another difference that names it 100 dollars difference for the tranny. It would be best to get the one with the same number of teeth on the output shaft if all else is equal. The gear to get the speedometer right is 10-20 bucks.
97 Mark VIII LSC/Silver/Gray leather
97 Cougar 4.6 Sport/White Opalescent Tricoat Metallic /Gray leather down but not out?
89 Cougar LS 3.8/Oxford White/Gray velour/HG need replaced AGAIN
00 Grand Marquis LS/Vibrant White/Gray velour
63 Falcon 302/black and rust/shed isn't moving
82 F-150/Oxford White/dumb VV carb doesn't pass emissions