Peeled back the boots on stub axle side....could see signs of the joint cup rubbing on the shaft. I'm just surprised this type of thing never happened with the original axles (the new cvds are double cardan like the standard plastic shafts the truck shipped with)....had expected these to be Rzeppa cv, since I hadn't understood that two cardan u-joints is a cv. I guess the original axles didn't have the big cup sticking out to rub on the driveshaft.
I can't change the EPA without buying a new transmitter. The stock Traxxas TQ doesn't support EPA adjustment. Will be looking for a replacement now.