Will a e39 diff fit ?

The E34 m5 does but I'm not sure about the E39. (E38 doesn't)

Email ed @ mwrench.com and ask. He can give you a definite answer.

hi there,

before you go changing ratios make sure you know what you want.

LSD makes the e31 fun to drive when you turn off the ASC but you really want to go 3.46 or above if you want to wake it up.

Did mine with 3.64 which is not as good as 3.9 but the 3.9 is not a common item (850CSi if you can find one).

With a 3.64 you will at least have half a chance of gettting from 0 to 100 in less than sixty seconds!

Given that mine is not my everyday ride and if I had a pick of ratios my first would be 3.9 followed closely by 3.64 then a 3.46. Less than that you may as well save your money coz you wont achieve much. These cars have a power to weight ratio that compare to a snail powered brick and unless you can find a shipload of extra power from somewhere the only answer is gearing it right.

Hope iy helps

Cheers

I notice you have a 850 not an 840. Most V12's came wit a 3.64 diff as standard. You can tell by the metal tag on the side beaing retainer.

The worst you could do is put in something with less numerical value than 3,64 unless you plan on breaking the land speed record!

Cheers