Timmer,
Attached below are the pics I found that I think you are looking for???
Includes the general rear brake exploded view and general rear axle for a 1-1/2 Ton (basic brakes/axle diagrams less the 2 speed pumpkin as they are same for all Series 4000-6000 trucks from what I could find) and the exploded view of the "vacuum shifted" 2 speed axle pumpkin (used the vacuum shifted pic as that's what was spec'd in the GM Heritage site for your
1949 Chevrolet Truck data).
I added the brake diagram in case it may help you get yours disassembled.

Let me know if there are other diagrams or details I may be able to try and help with (should probably go in a new thread to keep this one about your original topic).

Dan