I was wondering how hard it would be to put the 94-04 dash into a '90 mustang?
It seems fairly complicated but im not sure.

Would the seats from a '99 (front and rear) fit in?

 

I have seen pics of a coupe with the SN-95 dash installed....I am sure it is a bit of work but not impossible. The rear seats I don't think would work from the SN-95 but almost anything is possible if you are willing to modify things...I haven't tried so I can't say either way but I do know that it won't just "bolt in".

 

the front seats will fit and the rear with some modifications i think installing a dash will be tricky and exspensive since the console and electronics might not match up