Thank you for the information. So I have a 1988 Longbed Chevrolet C1500 with the Silverado trim for which the previous owner added modifications, most notably the GM Goodwrench 350 engine, to where he re-badged it SS350? The previous owner originally told me that he made so many modifications that it could fill a file cabinet so I did not get paperwork on the history of the truck.
I get around 18-19 mpg city and I suspect that the hard shell on back helps that. The truck rides like a car and the engine gives me all that I could want from a truck. I like having the SS350 badging, blacked-out grill, air foil, and the black center-cap with Chevy emblem, because if nothing else, it signifies that this is no ordinary Chevy pickup even if it is a faux SS.
My future may hold an original SS Chevy Silverado someday :-)