Just about finished rebuilding the AU engine to go into my EF XR6. So far so good but now need to fit an EF harmonic balancer.
I have a harmonic balancer off an EF engine which has 35 teeth on the back. and I have a new AU one that also has 35 teeth on the back. Recall reading somewhere that they are different. Are the harmonic balancers on EF and AU the same? thanks guys

Yeh they both use the same crank sensor, so theyre both the same. I'd use an AU one seeing as its an AU motor, and if theyre both second hand just because its newer.

Only real difference I know of is the way you remove them. AU needs a puller with L shaped legs to pull from behind the pulley. EF/EL is removed with bolts and a traditional puller.

AU one may be lighter too. Looks like it might have less metal in it. But is more of a pain in the a** to pull if you need to get it off again.

I dont think theres much difference in weight between the two, if there is its not very noticeable as I had the two off at the same time.
There is however a fair difference in the cam/aux shaft sprockets, AUs are a fair bit thinner and lighter.