Please can any one offer advice. The symptoms: Will not drive in normal high/low drive, makes a crunching noise when attempting to drive, noise from rear end. Will drive when the diff lock is engaged, Primary gear box seems ok as does transfer box. Thanks

Working from the roadwheel inwards (also read as easiest to check to hardest to check)

Driving member
Stub axle to half shaft splines stripped
Half shaft to diff splines stripped
Bearing/pinion/crown wheel in diff exploded/damaged/stripped

Can you rotate the rear prop by hand - chock all four wheels, release handbrake and take it out of gear then turn the prop shaft - do you get the same/similar noises as when you try to drive it?

Thanks for prompt reply, I will give it a try and let you know how I get on, Thanks again