4X4 MT 75 box is still available from ford as i have replaced two in my car as it munched the box that was in the car when i aquired it and then munched the replacement just after 5K and just after the years warranty was up, first box cost just short of 500 quid, second box my mate at ford worked wonders with the trade and i walked away with the box for 396 quid, transfer box is no longer available so it will have to be swapped off of your old box so it is best for a professional to do the job for you, big horsie power in 4x4 cossies=headaches with the drive train, best solution imo is the quaife box but it costs silly money.

C L