I have a 1999 Expedition 4X4 EB with 17" tires. My 1999 owners manual on pg 123 states only 3.73 rear axle ratio for 4X4 with 17's. I bought it used and have no window sticker. I have checked the door panel sticker, the glove box and I have craweled under the vehicle twice looking for something telling me for sure the ratio. I can't find anything. Another 2000 Ford owner said their manual showed a 3.55 axle only, for a 4X4. By the way, I have the 5.4L Triton V8.
Does anyone have any ideas where I can look for codes, etc.

I need the info for towing.

Thanks,

 

There should be a metal tag bolted to the differential cover. The tag will have something like 3L73=3.73 limited slip, 3 73=3.73 non-LS. If it has 3.55 gears, then it'll be 3L55 or 3 55. This is, of course, assuming that the previous owner(s) didn't change the gears to something completely different.