This 1980 GMC Sierra 15 half ton represents the middle of the Third Generation of the Chevrolet/GMC  C/K truck line produced from 1973 through 1987.  At the time the third-generation redesign was revolutionary in appearance at the time as it departed from typical American pickup truck designs of the era.  The third-generation trucks are colloquially known as the “Square-body” or “Box-body” generation.  What makes this truck interesting, besides the fact it is an unmolested one-owner truck with only 65K miles is that is it still equipped with the Oldsmobile-produced 350 Cu In (5.7L) LF9 Diesel that it left the factory with. This pickup version of the LF9 produced 120 hp and 220 ft⋅lb of torque.   In the late 1980s, Oldsmobile developed several diesel engine options that were based on converted gas engine blocks.  GM placed these engines in a variety of vehicles in the late seventies and early eighties to improve the company’s corporate average fuel economy.  The experiment was a miserable failure for GM as reliability problems plagued these vehicles and many ended up being converted back to gasoline power trains at no cost to the owners.  Consequently, this specimen is a very time machine in very restorable condition that will be the talk of any car show you enter in.