I have a factory T5 WC previously enjoyed, and used a 8.8 2.73.. I find it too high for 2nd, 3rd 4th.. but 1st is perfect.

T5Z has a significantly higher 1st , with 2 3 and 4 comparable to my factory T5.. THis way the 3.27 ends up perfect for all 4 ...

The reality is this setup got me on the road - but 2 years since i finished the build I want better gearing, on top of the fact that the old T5 is exhibiting symptoms of wear... So... I'm on the hunt for a locking 8.8 3.27... once I find one, i'm buying a T5Z brand new.

Of the thousands of Ford rear differentials that I have replaced/rebuilt, I can't recall ever seeing a 3.08 geared 8.8. I have seen many 3.08 geared 7.5's though. If it was for my car, I would buy a new gear set.

Not sure if it is a direct fit or not but the new generation Mustang's often come with 3.08 gears.