Would an AOD out of a 89 3.8 work as a replacement for my 5.0 AOD
Probably not as long as you'd like... depending on how heavy your right foot is. There are fewer clutch disks in the V6 version unless it's from a 89 SC.
It would bolt right up? input shaft and bell are same right?
Yes, it will work. It's the short tailshaft version. Remember that it's also set up for a floor shifter so if you don't have one, you'll have to get the shift lever flipped over. I had a 1990 Cougar AOD in my '88 Thunderbird and it gave me no problems whatsoever. I believe the '88 torque converter was reused. Shifts were just fine.
ok trans are the same , i had the same question, what about the driveshafts are they the same length?
MN12 and Fox driveshafts are totally different.
Driveshafts are different but the tail shaft is the same so you can reuse your old drive shaft right
Yes, no problem there.