Also to add, If those wheels do not have the (FORD) logo on them, they are NOT OEM. I never had any problems with my OEM 03-04 Cobra wheels. In fact they fit better than these knock offs that I have on the car now!
Measure the backspacing. I know you said it was 6.12, but something simply isn't adding up. Your wheel sticks out on your car. It sticks out on a friends car. If your friend has the same wheel, then there you go, compare the two. Yours is gonna be significantly different. Just because it's stamped that way doesn't automatically guarantee that that is what it is. (Elsewise, there'd never be any threads about how other parts that were supposed to fit didn't)
Jeez bud,....they're wheels. They either do, or don't fit. They don't fit for a reason. They're not right for the car.
I had 17x10.5 Pony R's on my last car. Everybody will tell you that those wheels will fit the rear of most any fox mustang w/ minor inner wheel tub hammering, and some wheel lip rolling. But......
You never would be able to fit my 10.5's on any fox body save one w/o mini tubbing the car though.
Most 10.5 Pony R's are 6.8" back spaced,...mine were 7.2". It didn't say that anywhere on the wheel though..... just 17 x 10.5. I knew that going in. I ordered them that way. Supposed to fit 93 Cobra.