Trans Mounted Parking Brake (C20)

[MtGMC]

In regards to your questions;

1,2: Its called brake/clutch lining. McMaster-Carr and others carry it in various thickness and widths. I think I used 1/4” x 3” when I restored my 56 GMC. You do have to rivet or epoxy the material to the metal band, or have an old school brake shop do it for you.
3. Parts hard to find. The boot is reproduced, the small springs can be procured locally, but the large bottom spring is all you get, don’t lose it.
5. Don’t know
4/6. I’ve got diagrams and adjusting instructions somewhere. The bolt is part of that. I will try to get you copies.

Mine worked great after I replaced the lining and adjusted the clearance.