So I found some brushes at a local badass old school hardware store and plan to put in some new brushes and swap the voltage polarity rather than swap the slip rings. (which would add a week to the repair).
I'll update wirh photos and I recommend anybody shoukd do this modification about 4-5000 hours and would probably extend the alternator to "lifetime of the truck". (Since 80-90% of the wear is only on one pole of the slip rings). Switch the polarity, switch the wear.
Now that I know how easy the cap comes off the VR I'll see if there is a way to open it and check the condition of the slip rings in place.
Update:
Photos of the progress. I'll update photo album and captions.
https://www.icloud.com/sharedalbum/#B14JsHvHoGjXxga
alternator back in the car with new holy shit tight belt (I had to loosen the idler pulley to get the belt on).
Perfect score. 13.6v on the battery buss. I don't know exactly where the vBat voltage is sampled but I know that 13.6 is the normal voltage on the OBC.
Sorry I didn't take a photo but the idler pulley between alternator and water pump has an offset center but it has a pin to index where it goes.
By loosening the bolt about 3-4mm it clears the pin and you can rotate the hub and gain maybe 1-2cm of length to get a tight new belt on. Then I was able to rotate the hub back to the proper indexed location.
By the way, don't be a moron and follow all the YouTube videos that tell you to use a T50 to release pressure on the tensioner: the tensioner has a 16mm hex head bump right on the arm for that purpose which is far less likely to slip off and take your pinky finger with it.