My Grandfathers and Father owned a fleet of Chevrolet trucks and have always told me the first problem that showed up was the need for a valve job. Then they would run good for a while but usually after getting the top end back in shape the rings would fail relatively soon, usually within a year to the point of doing a overhaul of the engine. He also said that the driveline would outlast the body of the truck. So, with care and service how long it lasts will be up to you.
