They bolt right in, the harnees needs a rewire, the 99-up seats are nicer. I just recovered/refoamed my 98 seats instead of buying someone else's used farted in 15+ year old leather seats with worn out foams.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.