58-59 GMC 1 ton Dually

[ERASER5]

I came across what appears to be a 58 or 59 1 ton GMC dump bed truck the other day. It sits were it died in a barn yard. One fender and the hood may be ok, the rest of the sheet metal is toast. The grill has a 370 emblem. My understanding is that the engine is lock or blown. The part that is interesting to me is the 5 speed tranny with PTO output and the split shift rear end. Is this a standard setup or is it unusual?