I have an '81 Silverado. I'm trying to find an original GM radio to install in my truck. I bought one on Ebay. This (it's a GM) radio/ cassette player is supposed to fit to '87. It's too big to fit through the dash let alone get through the dash bezel. All the other radios I've sen on Ebay for my truck year, have the same measurements. I have the original GM option code for the radio that was installed at the factory, but that doesn't help me. Can any of you guys help with info, or advice?