[mrmustang]

There are marked changes and when you are looking at a specific car, you'll want to know the FFR chassis number:

MK I
Mk I.5 (affectionately known as a tweener, could have backbone in the transmission tunnel, or curved bar for upper trunk, but not both)
MK II (adjustable doorhinges, curved bar in the upper trunk, backbone framing in the transmission tunnel, better mounting for front control arms, more adjustment)
Mk II.5 (some received removable transmission mounts and tweak to rear frame)
MK III (removable transmission mount, wider body flares in rear, slight tweak to rear frame to allow larger wheels and tires, change to front "X" member, tweaks to engine compartment to allow the use of the 4.6L drivetrain)
Mk 3.1 (minor tweak, 1st time offering of the "complete kit"
MK IV (current design, completely revamped chassis, suspension tweak, complete new body)


Do not take the sellers word as to what he/she is selling, which is why the chassis numbers are important to know.

Hope you find this helpful

Bill S.