Can you put a different stereo system in a 1992 cadillac sts?

We have been looking for some kind of kit to put a different stereo system in our 1992 cadillac sts. However we have not had much luck, and it seems that know one thinks it can be done.?Any one out ther with any idea we'd appreciate them.Thanks. P.s. reason 4 replaceing is the other doesn't work at all.|||go to a local car audio shop or even best buy or circuit city and tell them what car you have and they will recommend speakers and decks that will fit your car