sierra foorumist inglismaalt:

lisaks nimekirjale;
3.64:1 7.5" for the RWD Cosworth (with 108mm drive-flanges)
The Granada Cosworth 24v diff is the same as the 2WD Cosworth BUT with Sierra compatible 100mm drive flanges.
and the 4x4 Cosworth is the same as the 2.8/9 Sierra's 4x4's
and 2.0 DOHC 4x4 is 3.92:1 in a 7" diff
and some 2.0 RWD DOHC's are 3.91:1 in a 7.5" diff
and finally some 2.3 diesels have a 3.14:1 7" (hens teeth)
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Box 10 is the axle code.
M=3.14 (7" or 7.5")
A=3.36 (7.5")
V=3.38 (7")
U=3.62 (7")
3=3.64 (7.5")
9=3.91 (7.5")
D=3.92 (7")
Might be worth mentioning that Granada/Scorpio diff can be used in Sirrea's BUT may need modifing depending on what beam you have.
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Another way of knowing what diff you have is to look on the diff ID tag (little alloy tag bolted to the rear cover, top left hand side) Shown in the picture circled in red.

There will be some numbers/letters (look at the top row),
EG. 83BG MC 362
The 1st set (83BG) is the case type (7" or 7.5") as there quite a few codes its not worth looking, the esiest way to ID a 7" and 7.5" is to look at the top mounting. The 7" has one long bolt/nut and the 7.5" has 2 bolts.
7" on the left, 7.5" on the right.

Next is the middle code in this case its 'MC' which is an 'OPEN' type diff (NON-LSD) basically ANY diff with 2 or more "A" in the middle code will be an LSD e.g. "AA" or "ADA" any other letters without an "A" in the code IS an open diff.
Finally is the numbers, 362 which is (simply) 3.62:1 ratio.
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AS you can see the 7.5" diff is big bugger compared to the smaller 7" diff

Don't be put off by this as the 7" diff is a strong sod (used in the 4x4 Cosworth remember) ALL the 7" internals are the same (except the ratio's and LSD bit) so even the basic 1.6 diff is bulitproof Cool
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The following diff are LSD.
ALL 4x4 Sierra's and Granada's (2.8/9 and 2.0DOHC and Cosworth)
Most BUT not all 24v Cosworth Granada/Scorpio (upto approx 1994 are LSD, after that they are 'open' type because the Scorpio 24v had traction controll instead)
All RWD COsworth Sierra (3dr, Saff, RS500)
Then you might find an LSD fitted as an option to any Sierra or Granada, but unlikely.