I was able to contact the original owner a little while ago..... he changed oil every 5K, fuel filter every 20K, K&N put in at around 20K and I quizzed him and he knew how to clean it the right way. He never changed the antifreeze, has original front tires that are about shot, never replaced the lift pump, never wrecked and most mileage was to and from work... . 50 miles one way. He worked construction and said the reason the inside was dirty is because when he got off work he was always a mess. Towing was minimal..... biggest was a 18' enclosed with some 4 wheeler's in it. I don't know if it has a "53" block yet but it does have rear disk brakes. Prob's he had..... said it was hard to get into reverse in the morning, rear caliper might be dragging, and maybe something wrong with the heater control's... . said the heater stuck on one time and then the next morning it was OK. It has never been modded either except for straight pipe and the K&N. He said it never used any oil and never had to ad coolant... ... do these have prob's with cavitation?