Back in 83-84, I drove for the local beet plant hauling beets in winter campaign. We ran leased trucks from Ruan. In the fleet we had 4 older Freightliners with John Deere engines. They were experimenting with them to see how they would perform in the beet haul. Had a lot of power but poor fuel economy compared to the Cummins. They were similar to what an 8640 tractor would use. Would that be a 619? Completed the campaign and never heard any more about them.