trans/rear combo

This link has the most comprehensive information I've found online about Torqueflite transmissions.
http://www.allpar.com/mopar/torqueflite.html

For the rear end, measure the axle tube diameter. If it is less than 3", you have a 7-1/4". If it is 3", and there is a cover on the back of the differential housing, then it is a 8-1/4". If the is no cover on the back of the diff housing, then it is a 8-3/4".