the radio will be single "din" and likely will need a mounting kit from best buy or other electronics/stereo shop to install anything aftermarket. Check out ebay for the original equipment stereo if you want to be original... otherwise, Pioneer makes damn nice decks. In an older Blazer with the shaft radio, you'll have to cut the steel around the housing to fit the mounting hardware. I'm going to be doing a project soon that will include my mp3 deck or dvd deck, 3 screens, 2 in ech seat and on on the roof, and some badass speakers... it's going to take about a month of cutting and fitting since none of the doors or panels have speaker holes... but I'll take play by play pictures through the whole project... should be good info...