Got about 1/8"gap and leaking tranny fluid like crazy...just got the project,looks as if po put some rtv in it. Will that work for that large of gag...66 with 396 and turbo 350..thanks

A gap there is a sign of incorrect assembly. Plus a gap there wouldn't leak: it's a sign of transmission seal failure or possibly a crack caused by the aforementioned incorrect assembly.

I think removal and correction is your only option.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

Gap is 3/4 the way around it kind of what I was thinking not put together correctly maybe bottom two bolts are stripped out we'll have to disassemble this weekend and check it out thanks for the pointer

A TH350 will absolutely leak there if I'm reading the picture correctly. It looks to me like the main transmission housing to adapter is where the leak is. The TH350 had the seal in the end of the tail housing which is not used here so the adapter would have to have some kind of seal as well as be sealed to the transmission housing.

Joel
Northlake, TX
5 Ultravans, 141 Corvairs and counting...