1/2 Ton Rear Drums with Part Numbers

[truckster]

I just completely replaced my rear brakes and thought I would share the part numbers in case anyone is looking for them. My specific vehicle is a 1972 K/5 Blazer, but this should work for any 1/2 ton.

Brake Drums - GM 89058331 / AC Delco 18B471
Brake Shoes - GM 19307571 / AC Delco 17280B
Brake Spring Hardware Kit - AC Delco 18K1597
Brake Adjuster (left) Raybestos H1530
Brake Adjuster (right) Raybestos H1531
Brake Spreader Dorman 21149

There were a couple of small things that weren't included in the hardware kit, particularly the brake adjuster return spring (the one that goes between the adjuster and the inside of the shoe). The drums are a more modern design than the original ones (see pictures) but the dimensions are exactly correct and they fit inside my rally wheels. The brake spreader is a little bit wider than my stock one, but it fits perfectly. It's nice to have rear brakes again.

[1970cstblazer]

Thanks for the info.

I believe the rear drums on 1971-72 trucks were finned originally. The 11"x2" drum on the left is the same smooth drum with the anti-chatter spring that my 1970 Blazer came with and still has.

[1970cstblazer]

Original GM part number for the non-finned 11"x2" rear drum for 1964-70 GM 6 lug pickups/Blazers is 3846271 in the 6/71 parts book.

Per the 9/79 parts book, the finned 11"x2" rear drum is GM 3989543, and that book lists that number for 1970.