Just bought a 62 C60.... Wanting to update

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Just bought a 1962 C60 dually with a 261. It used to be a dump bed but now it's a flathead. It drove great on the test drive but I heard some noise coming from the rear axle area. I got the truck for a decent price and drove it home. It did great on the way home. Next day I drive it and on the way home I got a horrible screeching noise when depressing the clutch. Probably the throw out bearing. Today the noise continued and the clutch pedal would stick to the floor. It's a 4speed with a 2speed rear end.

So my question is, is there a common rear end swap that can be done easily? Or better yet is there a good donor vehicle I could swap the cab onto to get a more modern drivetrain and better brakes? I'm not afraid to fab some stuff up. Just thought I would ask here first.

I tried doing a search and read a lot before I posted this without finding many answers.
Thanks!
Jake