I run Amsoil severe gear 75-140.
Here is an update on the issue, I may have jumped the gun do to prior trauma from all the failures I have had with aftermarket parts in this axle.
I pulled the cover and found nothing wrong.. The oil looked great and the lower magnet was not full of metal. I jacked the rear tires off the ground and spun and inspected everything visually as much as I could without taking everything apart. It all looked great. Although there was more material on the dipstick magnet than normal I found nothing.
Also the mag-hytec cover looks square from the outside it is actually very smooth on the inside.
I did however notice that the bushings on my zone control arms have completely failed recently. I think the noise I was hearing is possibly from the axle rotating up under load towing my travel trailer and it was creating u-joint noise. I called zone and they have a new bushing design that does not fail so quickly.
Regardless I am still building my other axle with a trutrac, AAM 3.92 gears “which will be REM polished”, just to have. I will swap it in and have my gear guy inspect this axle under my truck now to see what he finds. Maybe nothing, maybe a bearing somewhere.
I also purchased a diff. Temperature gauge to help me with the PTSD this axle has caused me .
MaxTow Double Vision 250 F Rear Differential Temperature Gauge Kit - Includes Electronic Sensor - Black Gauge Face - Blue LED Illuminated Dial - Analog & Digital Readouts - for Trucks - 2-1/16" 52mm
https://a.co/d/c6TrmMq