I have a '63 with late wheels. It's a tight fit, but they seem to work just fine. My '65 (SRW) has the same brake drums, and I have drums that came off a DRW '63 that are also the same. (13" x 2-1/2") Lots of other trucks I've seen have the same wheels on them.

I'd guess your '64 has the "wrong" rear end under it if the drums won't clear 16" tubeless steel wheels. Some earlier stuff used 14" brakes IIRC; not sure how far back, though. The GM heritage center scans have 13" x 2-1/2" listed all the way back to 1960, so it would have to be the previous era or earlier. The HO72 dates all the way back to 1947 (IIRC), so someone may have done some swapping at some point.


Some of my crap:
1963 C-30 flatbed dually 292/SM420
1965 C-10 LWB fleet 250/column shift 3 speed
1965 C-30 9' stepside 250/SM420/4.10 gears (my DD)

Website I made for my crap:
http://www.66submarine.com