I said the 4-53 Detroit was a poor choice, because it's a 2-stroke with a very narrow power band. It's also much heavier than the Onan/Cummins in the picture. The Onan engine was inherited by Cummins when they bought Onan. It was developed as a power generator engine by Onan, and Cummins sold it to UPS as an alternate engine to the 292 Chevy and 300 Ford inline sixes they were running in their box trucks. These three engines were used interchangeably, with the same bellhousing, transmission, and clutch, all GM parts. I think the trans was a New Process 235 4-speed. The adapter ring on the Cummins has the Chevy V-8/292 bolt pattern. The Ford engine was used with an adapter plate for the GM bellhousing shape.
Unfortunately, Cummins was not able to supply spare engines in enough quantity to meet the UPS demand, so a retro-fit to a different medium-duty diesel was made. Since US does not sell their retired trucks for salvage, I think the purchase my friend and I made must have been a one-time deal with the local UPS shop. The engine will work well in a pickup or 1-ton because of its high RPM capability, (3,600 RPM) much higher than most industrial-rated diesels.
Jerry
