The 5th gear syncro's started going in mine when I was in Cook Town, so I headed south with it poping out of gear occasionally but by the time I got home to Brisbane it was wedged in 5th with a knee locked behind the stick holding it there.
The only way to fix it is to strip the box down.
A new bearing kit was about $300, and you can throw a couple more hundred at it for syncro's and maybe a cog or two, so the Pedders price is a little on the high side and if you are going to re-build it, I'd advise paying for someone to strip it and do it properly. It does cost more, but you're paying for the specialist tools to do the job and their knowledge.
Dropping the box is a bit of a shit of a job as the vehicle isn't quite high enough to work under, nor tall enough to slide the box out from under once its on the ground.
I managed it with a some ratchet straps around the chassis rails so if it slipped it didn't land on me, a trolley jack and a skateboard. Once the rear cross member and tail shaft are out, let the lot sag on the engine mounts and stick a block of wood on the front engine cross member under the sump, it makes getting the box back in so much easier as if the motor drops into its normal position its almost impossible to line up again.