hi there,
do it! its the best thing ive done to my series II.
ive fitted a disco 200 with 10 spline 3.5 diffs, Td5 cross flow intercooler and a 300 Tdi defender K&N... . .. it gose like a rocket!! 70mph easy! you can run a series G/box just dont give it beans off it the line else your brake a half shaft or strip Frist. its also pretty good on fuel if you drive it carefuly.
any qustions ask.
ben.............