Originally Posted by Chevyman87
I swapped my 700r4 transmission for a TH350. When installing the transmission I ran into 2 mounting issues:
1. The mounting bracket would not line up with the hole in the crossmember
2. The bolts I was using to hook up the TC to the flexplate were HARD to turn
... To mount it, I used the same bolts that came out of the 700r4 trans mount and ... I installed the old bolts to mount the plate on the transmission and ...
To fix the HARD to turn bolts, use standard thread rather than the metric thread. ...
(1) TH350 mount bolts through 1976 are AMERICAN threads. Bolts after 1976 are METRIC threads, the same as the TH700. If the TH350 case casting number starts with "6", it has AMERICAN bolts. If it starts with "8", it has METRIC bolts. The same rule applies to the speedo retaining bolt in the tail housing, unless someone had forced the wrong bolt into the hole previously.
(2) ALL TH350 converters with threaded pads through 1976 used AMERICAN bolts. SOME TH350 converters after 1976 used AMERICAN, and the rest used METRIC. TH350 converters using nuts and bolts to attach can be used either way.