Quick question guys. How do I know what gears I have in my truck? I am pretty sure it has to do with a letter in the VIN, is that correct? And if so, what letter stands for what gear?
Thanks!
Bill

 

I for the rear end, look at the tag on the pumpkin. a 3L73 is a 3.73 limited slip. 373 is a plain 3.73. The main gears for the F-250 and 350 were 3.73 and 4.10 gears. Some axle codes are on the sticker and if yours is there here are the axle codes.
31 — 3.73 non-limited slip, F-250/Excursion
C1 — 3.73 limited slip, F-250/Excursion
32 — 4.10 non-limited slip, F-250
C2 — 4.10 limited slip, F-250/Excursion
33 — 4.30 non-limited slip, F-250
C3 — 4.30 limited slip, F-250/Excursion
36 — 4.56 non-limited slip, F-250
C6 — 4.56 limited slip, F-250
41 — 3.73 non-limited slip, F-350 (single rear wheels)
D1 — 3.73 limited slip, F-350 (single rear wheels)
42 — 4.10 non-limited slip, F-350 (single rear wheels)
D2 — 4.10 limited slip, F-350 (single rear wheels)
43 — 4.30 non-limited slip, F-350 (single rear wheels)
D3 — 4.30 limited slip, F-350 (single rear wheels)
46 — 4.56 non-limited slip, F-350 (single rear wheels)
D6 — 4.56 limited slip, F-350 (single rear wheels)
61 — 3.73 non-limited slip, F-350 (dual rear wheels)
F1 — 3.73 limited slip, F-350 (dual rear wheels)
62 — 4.10 non-limited slip, F-350 (dual rear wheels)
F2 — 4.10 limited slip, F-350 (dual rear wheels)
63 — 4.30 non-limited slip, F-350 (dual rear wheels)
F3 — 4.30 limited slip, F-350 (dual rear wheels)
66 — 4.56 non-limited slip, F-350 (dual rear wheels)
F6 — 4.56 limited slip, F-350 (dual rear wheels)
81 — 3.73 non-limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
E1 — 3.73 limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
82 — 4.10 non-limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
E2 — 4.10 limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
83 — 4.30 non-limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
E3 — 4.30 limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
86 — 4.56 non-limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
E6 — 4.56 limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
88 — 4.88 non-limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
EW — 4.88 limited slip, F-350 chassis cab, narrow frame (dual rear wheels)
78 — 4.88 non-limited slip, F-450 chassis cab
G8 — 4.88 limited slip, F-450 chassis cab
75 — 5.38 non-limited slip, F-450 chassis cab
G5 — 5.38 limited slip, F-450 chassis cab
GW — 4.10 limited slip, F-450 chassis cab
98 — 4.88 non-limited slip, F-550 chassis cab
K8 — 4.88 limited slip, F-550 chassis cab
95 — 5.38 non-limited slip, F-550 chassis cab
K5 — 5.38 limited slip, F-550 chassis cab
KW — 4.10 limited slip, F-550 chassis cab
75 — Dana 80 (11,000 pounds GVWR), F53 recreational stripped chassis (motorhome)
95 — Dana 135 (13,500 pounds GVWR), F53 recreational stripped chassis (motorhome)

 

Thanks for the quick reply. Looks like I have 3.73 limited slip, according to the door tag. Thanks again!

 

Mine doesn't have a code. . . what is it then? Can it be identified by the VIN?

 

look at the tag on one of the diff cover bolts, the number is stamped there.

 

Thread moved to Super Duty forum

Oh, and it might help if you give us some details on your truck too Hiflyer746 - It could be either a 3.55, 3.73 or 4.10