Tuff 150 amp alternator

If you have a GOOD DVM, one that measures TRUE RMS. measurer the DC voltage at your diodes, then switch your DVM to AC voltage. In a perfect world it should measure 0 VAC, but it won't you should get a very little VAC, Depending on your set up if you have a significant VAC then the diodes are leaking too much.
Disclaimer: I have been out of the industry for over 25 years and just am now just starting to heal from a bad health crisis since Nov 17th. So I can not think of the VAC you should be worried about. If I find it I will amend this post