aftermarket stereo for 1990 eldorado bose equipped
 

I bought a 1990 cadillac eldorado. I love it,only 70,000 miles, canary yellow color, canary yellow leather interior. Only thing, It has the original stock stereo and the tape deck is broken,so I want to put my panasonic deh 1500 cd player I bought a few years agoin. I bought the scosche gmda connector kit. (Even though the packakge calls for a different connector for my year car, when I tore the dash apart the first time i realized that the gmda connector was infact the correct one for the factory wiring.) Now the back of the connector package says for bose equipped vehicles I have to purchase the fai-3a bose interface. My question is Do I HAVE to. I called an audio place and they said alot of times they work without them. So I am wondering if anyone knows if I can just plug in the gmda harness and skip the interface, before I rip my dash apart again. and yes my car is bose system