O/T How to find out what gear ratio your truck has?

We're working on a deal for a replacement truck, but we've learned that the '04 F350 had a few different configurations.
It's got the 6.0 Powerstroke diesel with single rear wheels, crew cab long box 4x4, and we've seen that it's around 9900 GVWR. Because our truck is usually towing when it's running, we're more concerned with the GCVWR. We've got a steel gooseneck 4 horse trailer, and an 18 ft flatdeck that pulls our 7000 lb tractor on occasion as well as 16+ loads per year of hay at about 5000 lbs. I drive past a weigh scale, and I've heard that the transportation officers are having more big loads weighed. I'm not interested in overtaxing the truck.
So, will the door sticker list GCVWR as well as GVWR? Or how can I find the rear gear ratio of the truck we're considering?

Sorry it's long, and thanks in advance for any help,

Jason

Check data plate and reference codes for axle- data plate should have a letter or number code somewhere in the mfg code that can be referenced as to axle ratio. On my old dodge pickups with same slant 6 engine and 4 speed transmission the next letter change showed 1981 had a 2.93 axle and the 1984 had a 3.54- was about half way through code line. RN.

Raise one rear wheel off of the ground, mark the drive shaft, then turn the rear wheel 2 revolutions while counting how many times the drive shaft goes around

You can do the manual way if needed. Jack up a rear tire, put a mark on the drive shaft and on the tire jacked up. Rotate the tire one revolution and count the number of revolutions the drive shaft turns. Make sure that the drive shaft marks you put on are in 1/8th increment.

Sticker on the door shows axle used.


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)

GVWR is what you will find on the door sticker. It will be less than the sum of the individual axle ratings.

GCWR is found in other publications. I found the one on page 5 at the link below, which might be good for ballpark, as it doesn't say so, but appears to be for '05 models. I don't know even what its source is so I wouldn't rely on it TOO heavily. Maybe one of the Ford enthusiasts, or even a dealer, can direct you to a better source.
Punch here and scroll down

should be a tag on one of the bolts that hold the rear cover on shoul say like 4-10 for 4.10 gears thats the way i would check because you dont know for sure if someone has changed the rear since it was new if they did the stickers might not match just my 2 cents

On your weight ratings, I would recommend you get in touch with your DOT enforcement office. I just checked into what it takes to be legal in Iowa for hauling old tractors to shows. Since Iowa uses the federal regs it's pretty simple for me. I'm under 26000lbs, I'm not commercial, not entering prize money paying contests, no sponsors helping pay any costs, not taking tractors to do paying jobs anywhere, and they are owned by me. The only rule that is the same commercial or private in my case is having enough tonnage on the truck license. For a pickup towing a trailer, the truck needs to be licensed for the amount the truck weighs plus the weight that the trailer adds to the truck.
Being a farmer will most likely qualify as commercial. Once you become commercial it gets pretty tricky. Of course other states and Canada may have other rules, so where ever you intend to drive I'd contact the DOT in each area.

If you take some emery clothe or a file and just clean the end of the pinion shaft on the end it will have the number of teeth for each gear in the rear end (ring and pinion gears) like 10-41. Then just divide one into the other and you will have the ratio.