Spent today figuring out which axle shaft is going to be just right. From others, it sounded like I was going to be using the front shafts and dealing with the extra length. Well that’s not the case with the 2004 STI. Fortunately, I can use the rear shafts. So with a 2004 STI you can use the rears, keep the outer CV on and then just switch out the inner with the front inner.
Here are the specs:
Axle / Spline Count / Diameter / Length
FFR 80237/ 29 / 0.935″ / 20.75″
2004 STI Front Shaft / 32-30 / 1.02″-0.9625″ / 20.75″
2004 STI Rear Shaft / 30 / 0.9625″ / 20.75″