I had another rear diff put in by a local mechanic and somethings not right... when its in L4 and I reverse with a bit of right hand down I get a loud bang from the back end and the passinger rear wheel jumps and skipps a bit ( this is on dirt ) .When I take off from an intersection while turning L/R (on road in 2WD) sometimes it feels a little grabby at the back wheels like the inside tyre is forced to turn faster than it needs to to make the turn, I can feel it grab on the road surface and hear the tyre tread slipping a bit.

If axle whs broken it would be undrivable wouldnt it ??

What would happen if he put wrong diff ratio in the rear ??

Any ideas ??