I have a 96 contour that has the 2nd DIN pocket but have never been able to figure out how to remove it, that might concern you.
I can't help you much on the mach 460 but I can say if you want a stock looking stereo Nakamichi falls in there pretty well. You could get a TD-45z
specs and a music bank changer like the
MB-70 
that's all I can add, if you are set on the mach 460, good luck!
-Pete
