Searched but no cigar...ML head unit change?

Have a ML320 built in 6/98. stereo shop looked and said it was fiber optic and had to keep head unit for it to work. I thought 99 & up were F/O? None the less is there any way to change the head unit and retain the CD changer? Is there a way to check what changer I really have? Can't believe the crappy sound quality compared to my 89' SEC(which I thought sounded pretty decent).

[G-Benz]

I believe the CD changers are made by either Alpine or Pioneer. The disc cartridge would be one way to determine which it is.

I bought mine in 10/98, and I was told that I couldn't get the later model (double DIN) head units, because they had the fiber optic wiring harness, whereas mine did not.

Check with a reputable installer...I have seen nice aftermarket installs in MLs before, and they seem to be able to get around problems that the dealership claims is not do-able.