Issues after truetrac install

I have a 2004 king cab xe 4x4. It has almost 315k extremely hard fought miles on it. I replaced the rear end with a truetrac about 3 months ago ( including new axle bearings, seals, carrier bearings, pinion bearing and seal). Everything seemed fine for a while and worked like it should. About a month ago it started making a metallic grinding/ spinning sound ( almost like a rock stuck in the rotor and dust shield). It only makes the sound after you drive a few miles ( it stops if you lightly touch the gas pedal) and everything warms up good. The shop that did the install replaced the axle bearings and seals again ( and charged me for it) but it still makes the sound. It is building up heat in the rear brakes. I replaced the calipers, rotors, pads, brake lines (stainless), and abs sensors. Still made the sound. I noticed play in the rear axles ( you could move them in and out about a 16th to an 8th in) and ordered new ones that were complete with new abs counters, retaining plates, everything. Installed those today, everything is tight, and it still makes the sound and builds up heat. I'm wondering if it is something with the b-lsd crap system that Nissan put on these trucks. Has anyone had issues like this or heard of anything like this?