Ok I was able to get into the shop today to measure, The Tbird measures 58" backing to backing, Thought I had it made, then I measured the plymouth, and its only 52", So all the sites with the measurements are WRONG!!!!!!!! Well I then measured the inside of the tires and rims that would have been used with the Tbird rear and guess what they are 52" apart.
So my question is would this still work? Even though the backing plate is 3" longer per side but the wheels set in farther. or will i need to get the axel shortened? or is it even possible to cut a IRS?