I am finally assembling the 904 and have the rear support, rear drum and the gear train installed but when i spin the shaft from the back of the trans in a clockwise direction i can hear the rear annulus rubbing against the rear drum.

I don't hear it in the anti clockwise direction.

Is this a problem?

The sprag usually makes a squeaky noise and it's only one way, it always sounds like it's dry no matter how much you have lubed it.

I'm certain its the annulus rubbing against the rear drum.I can see the contact pattern.

Check the end play or lack of it. That will tell you if you missed a thrust washer or something else is a problem.

End play is 0.026 for the gear train. It does the same thing with the old rear drum i have replaced. Specs call for .005 to .048. What prevents the shaft from moving to the rear in operation?

The output shaft ball bearing in the tail housing prevents output shaft for/aft movement, if you don't have the tail housing installed yet that's your problem.

Thanks John I'll give that a try and see if it helps.

Thanks John!!! I installed the rear bearing and housing and its now nice and quiet!