[GreenStreak]

Hey folks,

I'm working on restoring a 1966 GMC C1000 with a 305E which belonged to my late grandfather. One of the things on my list is addressing any issues with the transmission. My family mentioned to me that the clutch needs replacing, which is the reason the truck has sat in a shed since ~2003, but I'm unsure if the clutch actually needs replacing and even what size clutch it takes.

It's a 3 speed manual which was originally a column shifter then converted to a floor shifter to circumvent the supposedly untrustworthy column linkage. I suspect it's a SM318 transmission, but I'm not sure how to verify that. Does anyone know a good way to determine which transmission is in the vehicle? Perhaps a model or serial number scribed onto it?

Secondly, the 65-66 GMC Maintenance Manual says it can be either a 10.5", 11", or 12" clutch. I've found replacement 10", 11", and 12" clutches readily available on RockAuto, LMC truck, etc, but no 10.5". If a 10.5" clutch is the one I need, any ideas where I could pick one up?

I plan to inspect the trans either this upcoming weekend or the next, but I figured I'd ask y'all so I could go into the situation armed with some more informaton.

Thanks for the help!