Re: what size tailshaft for AU 4speed in EA
The yoke splines at the front of the tailshafts are the same. The rear uni mounting (as well as the material the shaft is made of and the type of uni's) is where there are differences.
Tailshafts are different lengths and have a different type of rear uni mount depending on which type of diff is in the car.
If you have an original style EA diff it'll have a yoke type connection and the shaft is made of steel.
But (getting to the point) whatever shaft was in the car should fit ok.
Nice swap mate, an AU engine and trans will give your car a nice lift in performance.. and a hell of a lot cheaper than reco's