Not in Houston, but I'd trust anything the folks at Morrow's Transmission in Pearland would say. They've done the TH350 in our race car, and the TH400 in our old Seville. The seville had a loose center support bolt that had beat up the case. They replaced the case, and split the price for the new case, since it wasn't included in the original quote.
We'll be taking our 68 Calais there to get the the TH400 rebuilt/resealed. They don't just work on old stuff, either. I've seen just about everything in there getting worked on. The owner even knows marine diesels pretty well. Mom and pop shop. When you call, you'll likely as not talk to Mrs. Morrow.
I'd trust them with any of our late model automatics, too. (281) 241-4181