i was wrong earlier on the size they are 255/35/18s on 9" rims
anther thing people forget is that most of the engineers that worked for Chrysler also spent time working for ford and vissa versa in the late 50"s threw the early 70"s and there are a lot of simular designs between the two Companies and if i remember right the guy who deigned chryslers 426 Hemi also designed some Ford motors so using mustang style spindles due to the availability and price is a logical choice
