good deal getting them apart! Cleaning the adjusters with a wire wheel, then applying a bit of heat may free them up.

As far as what type of brakes you have, you can look at an online manual.
here is 48-51 http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0503.htm
here is the 54 http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0513.html


Mike
1955 Chevy 6400 ex-flatbed (no bed now!) sold September 2023
In the Stovebolt Gallery
1958 Chevy 6400 flatbed W/dump
In the Stovebolt Gallery
1959 Chevy Suburban Owned for almost 20 years, Daily Driver -- sold May 2016
In the Stovebolt Gallery

Sufficient unto the day is the evil thereof