Probably a stupid thread but I wasn't finding anything by searching (or maybe I'm just too lazy).

My truck is a bone stock (drive train wise) 1977 highboy with a 351m and an np435. The motor was either rebuilt or replaced about 7 years ago. Knowing the shop my dad took it to, they likely didn't replace the original clutch. It drove great for the last 7 years but has recently developed a fair bit of clutch chatter when leaving from a stop in 2nd gear, but no other times does it chatter. Never did this before. After the motor was reinstalled it drove perfectly, so this is a new problem, which likely rules out the clutch wasn't correctly aligned (at least in my mind). It's more likely that the clutch is either worn out, or some oil leak has ruined it. Either way, I wouldn't mind putting a new one in there.

I'm really not looking for any major modifications, I'm completely happy with the stock clutch. I'm not opposed to a simple bolt on mod tho.

Looking on RockAuto, there are several different types and I'm not sure what to get. Thoughts?

Also, the chance of there being one or several leaks back there, what seals or gaskets or smart upgrades should I consider while everything is apart? I'm thinking rear main and .... ?

I appreciate the thoughts!

 

Rear main would be the one to look at, and anything that is coming down the back of the motor.

A clutch will chatter without oil. If you get a little slip and you get patches of clutch disc material stuck to the flywheel or pressure plate, that will cause it. If you overheat the clutch and the pressure plate springs suffer, that might contribute as well.

Buy the best "standard" clutch you can, of the same design as your existing clutch.

Get the flywheel resurfaced as well, and inspected for cracks. Just say "no" to cracks BTW.

 

Yeah, resurface the flywheel. Replace the clutch disc, pressure plate and throwout bearing. In the end of the crankshaft you'll see either a pilot bearing or bushing. Bushing: check for wear, if okay you can leave it. Bearing: I would replace it, just because. But these can be a bit of a pain to remove the old one unless you have a slide hammer bearing remover, there are other "tricks" to removing the bearing in case you don't have a puller.
While you're under the truck, check the clutch linkage for wear.

 

I’ll second what the other guys said.

Resurface the flywheel. Don’t put a new clutch disc/pressure plate assy in there and not surfacing it. Your just asking for problems and or reducing the service life of your new parts.

Bushing and or bearing.....just automatically replace it. For the cost of the part.....it’s cheap insurance.

 

Should've mentioned it but yes, I'll absolutely be resurfacing the flywheel. I considered that inclusive to a new clutch.

I was more curious about things like "this cable is a bear to change with the tranny in" or anything on the back of the motor. I can't think of anything but thought I'd check on here.