Newbie Mustang Question....if this will upset up do not read

[jmel]

The 8.8 rear only arrived in 1986. All mustangs prior and any 4-cylinder mustang has the smaller, weaker 7.5 rear end. "8.8" refers to the gears dimensions. Therefore the 8.8 is much stronger than the smaller rears. You didn't say what year your car was, but if you have a pre'86 car, you have a 7.5 rear, unless someone has already upgraded to the later rear.