Diff shudder :(

[MudRunnerTD]

I would not take it anywhere near a dealer unless you want to take out a second mortgage. I would find a decent 4wd workshop and ask them to take a look.

I expect you have a H260 rear diff which is the bigger diff. before you spend upto $2000 on a locker or a rebuild I would ask someone to open it up for a look. This would mean taking the third member ( the diff centre) out and clean and inspect it. Before that even I would maybe take it to a diff specialist and ask them to go for a drive with you.

Once stripped you can determine f it's the LSD or the Crown wheel and pinion. If it's the LSD then swapping out for a locker may be viable or finding a second hand LSD might also work. It could be a uni joint?

A Dealer would not get a first look let alone a second look though.