Sheesh . . . if you are thinking Ford 9 inch, then why not go with Mopar 8.75 ??? There were many made for your car . . . just an FYI . . . as was mentioned before, depends what you want to do with your car. I have a 74 Duster360, original 360, 727 auto. It had original 8.25 rear end with 2.94 gears, thought I would like more, so got 3.55 sure grip installed. However, I like driving long distances . . . so these really didn't seem like what I wanted . . . before going to Carlisle, PA show in 1999 I swapped out complete rear for another 8.25 with 2.45:1 gears ! Much happier !!! The 360 still cranks over the right tire (yes one legger) no problem, travelling down the road at 75mph, engine ticking over at 2600rpm, and mileage around 22/23 mpg all day long ! . . . Just my two cents worth . . . build the car YOU want ! . . .

Cheers

Mark