Diff problem ! swap large case e32 750il diff into e32 740i/iL

[e30luv318i]

Hey guys . I was doing my 3.15 that apparently came from a 750. The out put flanges look the same but the input where the drive shaft goes is way to small ! Do I need to swap the input flange or did I get a med case diff !??

[shogun]

I could find these pics
BMW Differential Tutorial, with pics.
http://www.bmwfanatics.co.za/showthread.php?tid=1374

Author: cvillebimmer Posted on: 2010-06-02
I have been under the impression that all e32 differentials were BIG CASE. Can anyone confirm/deny that?
I'm looking for a 3.15s from a pre 1990 750il to swap into my 735i. I figured it would be a direct swap until I received the response below for my wanted ad. Now I'm having second thoughts. This gentleman has a 188mm medium case 3.15 ring and pinion gear set that he's trying to sell me for my case. I'll get under the car to measure my diff this weekend.
you know that the e32 750il case is NOT bolt on to your car right? I had the identical car last year and had the v12 big diff on the garage floor next to the I6 medium unit.
just FYI-
the e32 750il diff is a 210mm BIG CASE. its mounting in rear is identical, BUT its nose is longer.
I helped my friend install one into his e34 530it with 6 speed, he needed a custom driveshaft. the e32 only has driveshaft length to suit the 188mm diff, I pondered the same issue with my 1990 735i-5
I wanted to install the S3.15 750il diff into it (my 2/90 build 735i-5) but comparing the 188mm stock diff to the 210mm v12 diff on the ground, they were not close enough for driveshaft.
I actually kept that diff and eventually sold it (probably 4 months back) to a e31 V8 guy.
if you have a big case 210mm diff already in your car, its easy to pop in another one, but converting between 210mm and 188mm is a different story.
the axels are also different sizes, my friend who built the e34 530it->540it 6mt had to change rear axels to larger diameter 210mm ones, also the mounting flange on the hub side needed to be changed to 210mm part along with custom driveshaft , even the e34 540i-6mt driveshaft was not a direct fit to the e32 750il diff- the flange depth was different length than 540i e34 6mt

http://www.bimmerboard.com/forums/posts/794017/
http://www.bimmerboard.com/forums/posts/793828

[e30luv318i]

My issue is I have two 210 mm diffs and the 750 has a smaller input then my 740 is this normal? Do I just swap 740 input to 750 diff ?

[e30luv318i]

For further reference: When swapping a large case e32 750il diff into a e32 740i/iL with large case (both large case) you need to transfer you input flange (drive shaft flange) from the 740 diff to 750. The axle flanges are the same. Also the VSS (speed sensor) appeared differnt but plugs are the same. I used the 740 vss