[BILT4ME]

I took measurements on the rear drums of our 70 GMC K2500 (4x4) as well as the measurements on a rear axle assembly I bought from a 72 Chevrolet 2WD (leaf spring) and dimensionally, they were identical. Both are Dana 60 with 4:10 gearing and leaf springs and drum brakes. I actually used the axle shafts from the 2WD unit in our 4WD unit because they were less worn.

I measured ID
Brake width
back-spacing from inside of drum to frthest point on brake area
back-spacing from inside of drum to farthest point of drum

I discovered (3) part numbers were within tolerance of each other. Each one was updated throughout the years.

I looked up the part numbers stamped into the face of the drum and had (3) different numbers. I then used the RockAuto site to find and cross-reference part numbers based on what I knew.

I bought drum P/N Centric 12366039 and Brake Shoe P/N Centric 11204190 They fit perfect.

Start on RockAuto with your APPLICATION and find the parts as listed. If you can't find that, then scrape off the rust on your existing drums and find the part number stamped in the face of the outside of the drum (where the wheel mounts) and Google from there.

I do searches through:
Rock Auto
O'Reilly
NAPA Online
General Google stuff
Summit Racing

I may find a tidbit in many or each in order to confirm a whole part. I usually try to confirm the data from at least two sources. Then it's still a gamble, but less of one.

Good Luck!