226/260/289/302 Ford. Installed in about every Ford car/truck until the 1990s.You might see tons of Chevy SB engine swaps due to them blowing up,but most vehicles that had the SB/"challenger"/Fairlane V8,still posess the original.
3.3 Chrysler.Chrysler's first FWD V6.Basic pushrod engine,but will last to 300K+ in a heavy minivan.
Ford 300-6.A big truck only engine.Could take huge amounts of abuse and not complain.Rarely ever see a 300 blowing blue smoke,even with 100s of thousands of miles.Ford refined it with EFI while GM and Chrysler phased out their straight 6s.
Chrysler Slant 6.An engine designed to an aluminum block,but got a cast iron one instead.Made for very thick castings,and a tough/rigid unit.Serious de-tuning,emissions strangulation,and frequent mechanical valve adjustments doomed the engine in the 1970s against up and coming V6s.However the engine lasted until 1987 in trucks,and longer in industrial applications.Low end torquey,but seriously underpowered in the 70s,nonetheless a reliable engine that skin flints loved.