Your gearbox will be either an FS5R30A or an FS5W71C. Variations depend on country, but typically the VG30E model in Australia had the FS5R30A and all other models had the other one, although with different ratios (so in other words, I'd need to know what engine and what part of the world you're in to identify the gearbox exactly). There's a table on page 142 of the service manual listing the different models and ratios for each.
Typically for Nissan, the FS5R30A box also seems to have been used in the 300ZX, Nissan Skyline R32 GTR, Patrol GU Y61 and the ZD30 Navara D22. The FS5W71C seems to have been used in the 240SX, 240Z, 280X, 280ZX.
You can buy refurbished boxes for just over the $2K mark, but rebuild kits are < $200 - would that suit?
Hi Tony, thanks a lot for your help. I am located in Pomona, QLD. I dont know which number has it but i will check that on Monday when i get to where the car is atm, at the mechanic.
All started after the service, very rare.just two days later while driving it started making a noise «clackt» and after the noise the car was losing the gear so not going forward. But i could drive it home trying few times after stopping, one it was running was okay.
Mechanic said gear 1,2 and 3 are fucked. 4 working.
It appears that (reading a few forums from the USA) although the 240SX shares the same gearbox number, it's housing is a little different with the shifter location further back (by about 125mm, so it's substantial). The internals are the same though - so if you wanted to rebuild yours, you could just gut the 240's box minus the shifter mechanism.
You might do better to chat to 4x4 who have a Patrol with its gearbox intact. I've bought from them before, they were good guys to talk to. At least you won't have to disassemble this one!