Josh,
What is your time frame?
We are developing a rear three link suspension for the Mustang at the current time. It should be available by early spring. We currently offer a Watts Link for the early Mustangs....
http://www.evolutionmsport.com/evmCa...products_id=38
The complete Three Link rear suspension will incorporate a Frame Mounted Watts Link, lower control arms, an upper link, rear adjustable stabilizer bar and bell crank driven coil-over system. The system will be bolt-in and will not require any modifications to the vehicle structure, beyond a few drilled holes. The system will have an aluminum link upgrade option and will be available in various "kit" forms.
Let us know if you have any questions.
Thanks...Mike