I have a 1996 1-ton Chevy pickup (with service body full of heavy stuff); factory 350 with the new-that-year central sequential fuel injection, turning an automatic with overdrive. The engine has a hard rattle on start-up, which mostly goes away as the engine warms. I figure somebody had a coolant leak and skidded a piston. Engines can keep going for years with this, but sooner or later I suppose I'll do an overhaul . . .
. . . with improvements. At least I intend them to be.