How do I tell what rear end gears I have on my 2002 PSD 4x4 Lariat? Does anybody know the RPO codes? I'm gessing that I have 3:73. Not for sure though. Matt

 

Is it an F250 or 350? More than likely its a 3.73 with the powerstroke

 

Its actually listed on the 'vehicle certification label', which should be on the door frame or jamb. The code listed under 'axle' is one of the following, depending on your model:
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)
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)
G3 — 4.30 limited slip, F-450 Chassis Cab
73 — 4.30 non-limited slip, F-450 Chassis Cab
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

There should be a metal tag on the differential housing that states the ratio. A "3 73" will be an open 3.73 gear. A "3L73" indicates a 3.73 with limited slip. Same format for the 4.30 gears

 

There is a metal tag bolted on with the diff. cover bolts that will list the ratio. If there are two tags, the second one is for limited slip.

 

Wow! Thanks for the info! According to the sticker on the door, I have the 3.73 with non-limited slip. What's the difference between limited slip and non-limited slip? Thanks for the helpful info! Matt

 

You mean besides the high repair cost if the limited slip breaks?

I spend time off road - part of my job. With limited slip, I don't often need 4wd, and when I do, the limited slip really improves my traction. I may be less likely to get stuck with limited slip. On the other hand, it means I'll probably just get stuck deeper...