The crossmember will have to be modified. Driveshaft has to be shorter, IIRC and you'll have to massage the trans tunnel a little. Other than that (and getting the TV cable/rod adjusted) it's a great way to improve mileage and driveability. I'd suggest at least 3.55 gears in the rear end though....I know my old Mustang has 3.08's with an AOD and 60 mph in OD is like 1400 RPM. Kind of lugs around.