I just got done with my huge swap project. I bought this 89 RS V8 T-5 to be a daily driver (cause I never roll in anything unless it has a V8 LOL) and I ended up putting it's WC T-5 into my 90(the beast). I then began the task of putting my 700R4 into the 89. Oh yeah, the rear end on the stock 89 (3.08 open) got run without oil and burned up. After finding a donor rear for 40 bucks out of another 89 RS auto with 2.73's (wrecked with no motor or trans) I swapped it in too. Here's a recap of all that I have done in the past two weeks to get the 89 running like factory:

-Bolted up the 700R4
-Swapped in rear end out of auto 89 (2.73 open)
-Bought speedo kit from Bowtie overdrives (700R4.com) to convert the VSS from the 90 to cable driven, and got the right speedo gears(red 17 and red 37), since the 700 was setup for 3.42 gears ( gray 15 yellow 41) that are in my 90.
-Got Automatic computer from 89 auto that had a Jet stage 1 chip in it, and swapped it in.
-Added pin # C7 on ECM harness for 4th gear input from the tranny.
-Wired up the Torque converter to the ECM and proper places Via electrical schematic.
-Hooked up TV cable
-Fabed up a contoured sheetmetal piece to cover the hole for the shifter and attached it with some sheetmetal screws.
-I saved the square of metal that was cutout of my 90 that had the autoshifter mounting points and pop-riveted it to the new sheet metal piece on the floor.
-Removed shift indicator light so it doesn't stay on when the TC is locked
-Transfered in the auto brake pedal and all the switches to it.

With all that stuff done the car runs soooo good and smooth. The Torque converter locks and unlocks just like factory and the cruise works fine, and the speedo is fine and I love driving it to work everyday. While I was doing all this I added a K&N filter and a flowmaster muffler that was donated by my 90 before it got the hooker cat-back.
The only thing that is not factory about my swap is the fact that the tranny has a BM stage 2 shift kit in it along with no accumulation springs, a 2000 stall tork master, a megashifter and a Vette servo which makes the L03 spin the right rear tire almost everytime it shifts, LOL. Hopefully I can get 26 MPG out of it!! PM me if you have any questions about the swap. Hope this helps

 

Woops...I think you wanted it in this forum.