there was a company years back that offered what they called a limo back glass. it did allow you to lower the glass like a blazer tailgate glass. these units were kinda pricey for their day, (something in the $500 range and we're talking early 80's). they consisted of a completely new glass, frame, seals, power motor and switch. i don't remember them being around long, but trucks were really just getting started good as customs. you might try some back issues of TRUCKIN' say 79 to 81. i do seem to remember them doing an install piece on one. if you wanted to try a blazer rear unit you'll need the intire rear section but with a removable top a surburban tail section might be a better option. good luck tim b.