Has anyone swapped a 300tdi transfer box into a td5 my td5 has centre diff lock but transfer box has died I have 3 tdi transfer box in the shed and just wondering what needs to be swapped so it will work with traction control and what not any replies much appreciated

The tdi box mas no high/low switch so the Td5 ECU will not know when it's in low to go on the proper fuel map for that but you can emulate that signal with a toggle switch on the circuit to switch it to earth when you select low with the lever.