Unlike you lucky late model guys, I still have the manual belt tensioner for my Alternator. The Prevost Manual says to adjust to 200 lbs using the Prevost Belt Tensioner Gauge, part #011742. Up to this point, I just kinda go by feel, but wondered if anyone has seen the Gauge or has a better way to assure the tension is within a reasonable adjustment. It does flap around at idle, but smooths out with just a few RPM's, no matter how you adjust it. I've seen others do the same thing, so I assume it's normal.

And NO, I'm not going to upgrade to the auto tensioner to the tune of 1,600.00 Mango bucks just so I have a new shiney part highlighted by neon lights in the engine compartment.