if you've got a 91 spec car and waht to fit the 92 spec dash in to it then there are no major problems, as long as you rememebr that there are slight differences in the instrument cluster (it's just slightly smaller) and that the plastic clip on the left hand side of the vent isn't broken
if you have a pre 90 spec dash there is a lot of fucking about and you basicly have to use every single bit from the newer dash if ytou want to swap over, including the steering column and all sorts of other stuff you wouldn't even think of, even the slider controls on the vetilation side of things as well as the amp casing and the lower kick panels
the good things baout it is that the switches for the fogs and screens use the same plugs for any of the post 97 cars
the lower portion is different but only slightly on the 91 and 92 cars but it's totaly different on the pre 90 spec cars
also the fittings for the centre console are different on the pre and post 90 cars as the screw holes are further back on the older versions