Peter J. Malanchuk

This is a Mack model B-71 which came out in 1953, when all of the new B series came out. This model may have the Cummins NH-220. The early Cummins 673 CID six had a 4-7/8 in bore by 6 in stroke, the successor the 743 CID six had a 5-1/8 in bore and 6 in stroke and the successor to the 743 CID six was the Cummins NHC which were 5-1/2 in bore by 6 in stroke with 855 CID. Foe a short period Cummins made the Super 250 which displaced 927 CID, same 5-1/2 bore but deeper stroke/sleeve.