It looks like a Fairbanks-Morse C-Liner. I can't tell you specifically which one. As I recall, the C-liners used the same body. The exceptions being the CPA-15-5, CPA-20-5 and CPA-24-5. Those last 3 had A1A rear trucks, instead of the B trucks used on the other models. The front truck was still a B, though.
Cheers,
Ben