For the GMC trucks that used a Pontiac engine, anyone know what the truck 3-speed manual trans is or what fits on that bellhousing besides the truck three speed? I found one and before I dive in I need to know what I can use the parts for. I seem to want to remember there is a change in the crank (besides the journal sizes) around '57, the flywheel doesnt work all the way across that range. What I'm primarily wondering is if I can use the clutch/bell/flywheel to run something like a 6-bolt case Olds trans behind a '60 389. The source truck would be a '55-'57, not sure which year.
I've bought and sold two standard shift bell housings from '55-'57 GMC trucks with Pontiac power, and both of them used the standard "Chevy" transmission pattern that many 3,4, and 5 speeds will bolt to. The only thing you may need is an adapter ring for the large center hole, depending on what gearbox you use.
Check out these threads from PY forum, they discuss some of the early interchange. I know that a '57 GMC flywheel will definitely interchange with a '58 Pontiac, as I made that swap. And a modern muncie 4 spd will definitely bolt up to a '58 bell housing. I have a '57 bell housing as well, but didn't check the trans bolt pattern. Read through these and if need me to, I can dig out the bell housings I have and get you some pictures. http://forums.performanceyears.com/forums/showthread.php?t=618642&highlight=flywheel http://forums.performanceyears.com/forums/showthread.php?t=543537&highlight=flywheel
As far as car bell housings go, '58-'60 housings have the "good" trans pattern, '56-'57 housings have the 6 bolt top selector trans pattern, and '55 housings have the 5 bolt light duty selector trans pattern.
I can buy the whole engine and trans combo for $500, I just am not sure it's worth quite that much. I know the truck is a 5-6-7 but not sure which. I do now have a couple of the 6-bolt selector transmissions here. And a couple of the Chevy case transmissions. I'll look into it and see what I can come up with.
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