I would assume this, as don't entirely understand your post, so I am
guessing here, that you have a GM factory radio with a factory cassette
mounted in the center counsel. You are attempting to change the wrong
piece...the radio and adapter you have will replace the dash mounted radio,
not the the lower cassette deck.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.