Hi, im a bit puzzled, ive been offered a diff, which im told is a ford sierra 7.5 inch diff 3.91 ratio non LSD. Ive cross referenced the code on the casing with a guide that was on here a week or so back (the code is 91BG AA 391,BOTTOM LINE READS 4A 1F27 5 015) and according to that it is a 3.92 7" LSD which is what im looking for. Can anybody please confirm any of these as im unable to check it physically. Thanks

Oh and i forgot to mention it has bolt on half shafts if that helps to identify it.

best bet is to manually test it, by trying to turn the outputs seperately. I too thought that the AA bit meant it was LSD.

3.91 non LSD from 2.0 DOHC NON ABS MT75 TRANSMISSION
AA = non LSD
AAA = LSD (three characters with more than 2 A's, i.e BAA, ADA etc)

by my records,

but like Joel says test it to see.


[Edited on 3/8/06 by givemethebighammer]

spreadsheet of codes attached

Hi Andrew long time how you doing with the car Graham

To be really sure wip the back
plate off ratio is stamped on the crownwheel.

any help?

http://fordsierraclub.co.uk/forum/viewtopic.php?p=100105

Here's a 7 vs a 7.5. 7 on the left and 7.5 on the right. Note this particular 7 doesn't have bolt on driveshaft flanges but could just as easily have them...
Rescued attachment 7vs7.5diffs2.jpg

Now 7.5 on the left and 7 on the right...
Rescued attachment 7vs7.5diffs.jpg

Hi, thanks for all the info guys, i can see now the 7 1/2" is much bigger, i foolishly expected it would only be 1/2" Are the 3.9 (ish) LSDs quite rare? How much should i really be looking to pay if i find one and also, do all the bolt on drive shafts fit (different diameter)? or are there some which wont