Sav diffs suffer same prob as T or EMaxx - the plastic lets the diff twist slightly under load and this lets ring and pinion pull away from each other and eventually strip or blow out.

Usual solution is same - stiffen assembly so it cant twist under load. Alum diff cup, metal diff case and eventually metal bulks. I upgraded my 4.6SS to Nova 7075 diff cups, gpm alum diff cases and alum bulks. Sav diff cup may not be as critical as in a TEMaxx where the 2mm screws just cant handle the shear load, but I went ahead and changed anyway. No more diff trouble with the stock 4.6, a 27Picco or Axial 32, but nitro doesn't have that instaneous BL torque either. Here's a shim reference-

http://savage-central.com/modules.ph...wtopic&t=55122