Help! Rear wheels locked up and wont go into gear???

[nikp_7]

So first I have a Nissan Patrol, GQ 92. Turbo diesel

Last night leaveing a bbq, id had a beer or two so wife was driving, leaving a driveway on a hill she chose second and turned onto main traffic.

It was obviously too high a gear n she struggled for a second before the rear wheels locked up and stalled. I quickly jumped in, started the car, the clutch had spring, went to select gear and as I released the clutch, nothing, like it was still in neutral. The car behind got out to help push but the wheels wouldnt budge. Luckily he had a snatch strap and he dragged me off the road. My wife noticed the front wheels spinning but the back locked.

At first I thought the clutch, but it felt fine, then I thought the gearbox had collapsed on itself and was stuck in gear, but this morning I realised if that was the case, the car wouldnt of started in gear

Im going to have a look this morning, there was no fluid leaks last night either, any suggestions what it could be.? Im gonna try reverse it, if that doesnt work, im gonna try put it in 4wd and lock the hubs and see if I can get the front end going.

Im prety lost with this to be honest.