In regards to having to swap TCUs when replacing valve bodies, I can't offer specific knowledge but can offer my experiences.

We have swapped 3 different valve bodies, installing one unit 3 times and the two other units one time each, and the mechanic didn't say anything about having to reset or swap the TCU, but that I might have to drive it a few days for everything to settle in and work properly. While they offered different shifting characteristics, they all worked "properly" (smooth, positive shifts, nothing weird).

The reason that we have done this is that although my tranny seems to be working 98%+ perfectly, it will sometimes shift a little "too" hard when kicking down from 2nd to 1st. The best way to duplicate the problem is idle at 20mph for a few feet and then floor it - it will often have more of a "clunck" then I think is correct. ?!?!?

However, this is the ONLY problem, the mechanic/shop owner has agreed to continue to work with my to solve this problem (and has shown some serious good faith in rounding up parts and swapping them around without charge). Since I only paid $1300 (total, including R&R) for the tranny rebuild (under $1500 including new rear main seal and several other minor fixes), I am pretty happy.

-David