Nissan Repair: Navara Transmission, nissan navara, grating noise

Question
1988 Nissan Navara DC Ute - manual 4wd diesel.
Helping student out - has no money- limited knowledge of these.
Vehicle on road would not move in any gear when clutch let out.  Loud noise like jumoping out of gear.   However, hold gear shift in gear same response.

Vehicle off ground in 2w/drive engage 1st and tail shaft and rear wheels turn.  Slowly apply  handbrake and loud clunking noise followed by grating noise.   Engine (on idle) does not drop revs rear wheels and Tail shaft stop.   Thought selectors but does not jump out of gear. Eliminated diff. because of above test.
I think gearbox but what is it likely to be.

Thanks in anticipation for help, as kid tight for money and I have limited knowledge of these vehicles.

Regards
Bill C.  

Answer
Bill,

This could be a blown clutch or the output shaft of the transmission being broken.  I would remove the transmission and check the clutch before taking the transmission a part.  While the transmission is out you can shift it through the gears and spin the input shaft in each gear and see if the output shaft spins.  But, since you say the clunk with it in first and the engine will still idle would make me think the clutch and pressure plate is blown.