Most have 8 1/4. Some (if not all) 66 Formula S models came with 8 3/4 but I'm not certain about the availability on 65 models. I have a dealer option packet around here somewhere for the 65 models that may have the information in it and will post if I can find it.

I use to know this but haven't messed with the car in a while and have forgotten some of the spec. info.


65 Barracuda
70 Challenger