Welcome here 1stGen;

I guess you will have lots of time to wrench seeing as your Oilers are out of it. Hehehe, sorry, I just had make sure you feel welcomed.

Anyways, you obviously are leaning towards a standard transmission. Furthermore, it would seem like you want an O/D. You might want to consider the T-56 however with the two piece rear seal crank that you have, you need to get a special flywheel. My son and I did this conversion and the flywheel alone cost us $700.00 if my memory serves me correctly. We did the conversion in an 84 T/A and we knew that the T-5 could not handle the power we were transplanting into it. The gear ratios are wonderfully spaced. The double O/D would force you to keep the motor on the mild side seeing as you turn 1800 rpm at highways speeds with 3.73 rear end gears.

Your other option would be to change to a one piece rear seal block and crank. I think you can buy those trannies used for $1,000.00 these days. When we did the upgrade 8 years ago, we paid $2400 for the tranny and clutch and pressure plate.