hi its a straight swap , uses the same speedo cable, you can use either the whole brake setup from exisiting or donor, i binned the old rod system and kept the cable setup from the disco,
the only issue i had was the new transfer box came from a 300tdi and i found the hi/low lever was in a different position on the spline and i had to move it round a bit.
i removed the transfer gear, fitted the box then refitted the transfer gear made life so much easier,
if the transfer box is a late one with the electronic speedo drive you do have to swap out but its 2 seconds to do.
what engine wheels etc do you have , i have a 300 with big tyres on a 110 and found disco box to be too much for it, think it would be fine on a 90 with normal wheels