you will need a double hump crossmember and all 4 of the exhaust hangers with the rubber pieces, check a local junkyard or some mustang parts stores like 50resto.com
Mustang 78 told you right. I did the same swap on my 85 and it sounds sooo sweeet. I also have JBA headers with a Bassani x pipe with cats and it is all that. You'll be happy.