Clutch advice

[Marc Rexroad]

Stock 79 c30. 350 engine.

Needs a clutch. How can I tell which diameter clutch to get so I can swap it out in a day?

Any recommendations as per make and such?

 

[fast68chevy]

could be 11 or 12 you jut never know but being a 1 ton its probly 12" and napa shows only a 12" clutch disc for 79 C30 350. and many of the 70s 350 trucks were 12"

so iif its stil stock factory original its most likely 12" it looks like,

10" was on 250 and other smaller motors
11" on 292 and 305 and probly the 4.3L 4 speed trucks too(1985-up)

but you cant know for sure til you pull trans or engine though. and most over the counter store replacements are LUK brand and are good. make sure you get correct throwout bearing. there is short and tall ones.. if you had a way to see backside of the flywheel and run the casting code off it before you pull anything then you could look it up and see what size clutch it is for...