[61superman]

i am currently using 1986 caddy seville disc brakes in the rear of my 72 burb. kept same 5 lug pattern and still running mid 80's steel wheels.
86 seville had rear disk brakes that uses rubber brake line with a 10mm x1.50
banjo bolt.
i am using stock 72 burb rear end with the caddy backing plate and brake setup. the only problem you will have is the parking brake cable but, POL (performance online.com) has solved this issue and makes the correct lenght cable when using caddy disc brakes. I pieced my setup together, but POL makes a kit for 67-72 trucks to run caddy rear disk brakes.