I have a 3.73 rear in my 81 and was thinking of changing the transmission to a 4 speed auto from a 82.  I wanted to know if this is just a bold in swap and if any other changes would have to be made.  I was thinking of this so that the RPMs would be less when crusing at highway speed.

I believe you need to add a new torque converter, have the driveshaft shortened and install a new kickdown cable & hardware.

I hope to do this swap to my '79 this year or the next.

A few members here have done this swap with the 700R4 and the 2004R. I'm sure they'll weigh in soon enough.

 

 

Starting my conversion this weekend hopefully. TH350 to a 700R4. In addition to what Kevin mentions, you need to check the placement of the crossmember and you'll need a modified shifter detent. LukesVette2010-02-03 18:32:39

When I changed my 78 from the TH350 to the 700r4 I had to do all that was said above and also move the E brake bracket over to clear the longer transmission. Belive me you will be glad you made the change.  You will realize a big improvement in your gas mileage.