Tremec swap to SM318 bellhousing? measurements on bell? (GMC)

[Chuck78]

I'm looking at options on a 5 speed trans... seems that I can retain the stock bell and starter, etc if I swap in a Dodge NV4500 with an adapter plate between the trans and bell. NV4500 isn't really what I wanted (heavy, and granny gear). A T5 would be ideal if it'd hold up to towing a car trailer once a year or so... Not so sure on that. Truck previously had a T5 swapped in, but last owner yanked it out, and I never got the details of how it bolted up. So that leaves an NV3500 or maybe my Tremec TR-3550 for my Camaro (like an older TKO500). 3.27 first and OD 5th... Bolts up to the same bell that a T10, ST10, Muncie, Saginaw, etc bolts to, which I believe is a T5 pattern also... Nv3500 means I need a $1000 adapter kit with starter and crank spacer, etc... NV4500 bell to trans adapter is only $300!

Anyways, I tried to measure my stock bell bolt pattern, and compare with my Tremec (new in box still). Looked to me that the Tremec pattern was almost the same, but the bottom holes were about 1/4" wider or narrower. Also, the input bearing retainer that acts as a bore register, not sure if it'd be the same diameter between the SM318 and the Tremec.

Lastly, how do you deal with the T10/Tremec/Muncie style where the bell is threaded on all 4 holes, but the SM318 style of the bell where two bolts thread into the bell, and the other two into the trans? Just nut and bolt it?


If someone could measure their bellhousing and post side to side and up and down measurements on the trans ear bolt pattern, and measure the input bearing register diameter, that would be MUCH appreciated... I have a GMC, so the block is an oddball that makes trans swaps difficult...

Thanks!

Chuck