Stereo Change out

I've got a 92 PA Ultra, my friend had a 1999 Escalade and removed the stock stereo and changer. He gave them to me, now is it interchangable to use the one from the Escalade instead of my PA's? Also I'm having the issue with the starter kill from the stock alarm, if you have the details on how to get that lower dash panel off where i can find the security controller, i'd much appriciate it. I posted about it a while back but never heard anything. Thanks yall....

99 'sclade and 92 'sabres have the same size radios(dimension wise) in 95 GM upgraded cars to the 32 pin radio connector, but the truck platform kept the old style. my 01 silverado has the same connector my 94 Buick does.

The radio should plug right in, the only thing I'd be worried about is theftlock. in the silverado forum, there is a stickied thread at the top of the page that tells how to unlock the radio. You may have to do this before it'll work.