diff

[s.hogan3]

in my 400 the diff is a 3.31 ive been told that i can use a jag v12 xjs diff at 2.88 or try and get a jag e type on at 3.07 but these are rear is there anyone here brainy to work out say at 40 miles a hour wote the revs wil be in each gear so i can work out which diff will match the engine speek as the 3.31 is far to low
thanks steve