Yes, if you didn't get a Mustang years ago...
Bought this Mustang from my brother about two years ago, it sat for 5+ years in his shop not driven. So, it was a project car and we've had to go through it but it is running great now. [351W bored & stroked to 408 w/4spd] I think I will drive it today!
Stev-o,do you know the rear axle gears ratio ?
No, never checked it but guessing it's 3:73? I dont like it, the motor is screaming at 75mph, my preferred cruising speed through the Hills. Not a priority but I'd like to lower it.
Be worth it to have a read on the tag on one of the rear gear 'chuck' mounting bolts.
I don't know if you have history on the car's past;someone may have installed those low-end gears at some point.
I'm curious if yours has a 9" rear gear-set or the 'small block' type 8" ? How many spline axles?
I would imagine that Mach 1 has the larger spec rear axle gear chuck,but either way,that rear tag will give you all the information you need,if it's still there..
You can find a compatible 'chuck' to swap in there(good posi traction)with the higher gear ratio you want;then save the original? 'chuck'/gearset when you go back to what the car came with.