The housings are the same pattern with different lengths of tubes. Brakes got larger with increases in gross weight. The brake sizes also increased as time went on due to DOT regs and increased speeds.

What you could probably do would be to take the drum assembly off a newer model and bolt it on to an older. You would also have to check the axle length to be sure it would still work. I know that you can interchange parts on the different years of axles.

They seem to have left the bolt patterns the same and used what is called "interchangeable at attach points". One example of this is the pumpkin swap, where the entire carrier assembly can be swapped, but the individual components won't interchange.

Fred
52 3600
69 C-10