If it is a cracked chassis try making up 4 rubber washers to go between the chassis and the subframe. It worked for me. Mind you the chassis crack might be gettin' bigger. Can't be arsed lookin' its not makin' a noise.
My Spendlander made a loud 'click' on pulling away from reverse just before the IRD failed. Have you check that your VCU hasn't siezed? Might be worth eliminating this possibility. Good luck!