The Divco milk truck is probably a Model U or a Model 11, short wheel base, I think 100", built from 1938 or so to the early 1960's with little change. The engine might be a Continental L-head 6 (218 cid - 226's were also used, but that doesn't look like one) or a Hercules 229.6 cid. A Nash six was also used, but I think that was the overhead valve Ambassador engine. The roof line was squared up in the early 1960's and that style ran til the end of Divco's in 1986, using Ford sixes.
