I have a 1997 GT with the Mach 460 HU. I was wondering if I could replace it with the HU out of a 2001 GT if it was the 460 also? Will they be compatible being from the different years? Can someone tell me where I can cross reference head units to see what will work? Thanks and sorry if this has gotten posted before. I went 15 pages back and couldn't find an answer.