Take a look at these. These are the big end bearings off of the Mack. Notice th oilling hole...maybe the reason the oil pressure was only around 30 PSI running down the HWY. Suppose to be 60 PSI. When I was driving down to Stephenville (before the UFO sightings ) I noticed a slight knock when coasting...didn't hear it accelerating under load...figured it might be a rod. We took it into the shop on the way back...mechanic said same thing. really close call...crank was ok, replaced all the rod bearings and mains, new oil pump, new rod on that hole (it was out of round and needed re-sizing), new rings. should be good for another million.