Just do old school and shimmy under the truck and read the tag on the diff?
This is how I did mine, no decoding, it tells what gear is in your rear end right on the metal tag......take a rag.

 

There are probably TWO tags. One says "75w140 synthetic only", the other has the gear numbers on it.

 

Hope this helps...

Axle
Code Type
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

That can be found here at FTE...see link.
https://www.ford-trucks.com/forums/s...d.php?t=139080

biz

_______________________________
2003 F250 SD SC 142" XLT FX4 V10 Auto 4x4 3.73s

 

Thanks biz4two. That confirms that I do have the 3:73 limited slip rear. Don't know if I'm happy about it though. From the advice given I'll replace the fuel filter, clean the air filter & plugs and report back with results.
I'm a bit lost on the mention of cleaning the MAF wires (krewat); again I don't see them stated in the manual, wondering how to properly service them and why they would need to be cleaned.

 

Something is seriously wrong with that truck. My gears are a little lower (4.30's), but I can pull a 10,000 pound camper up a posted 10% grade well over 60 mph (as fast as I wanted to go at the time because side winds). The truck only kicked down to fourth gear.

 

Try the easy stuff first won't cost much, then you will know it has been done. more then likely this will fix your problem if not then you can look in to the other things.

 

you said you live in S.D. Are you having problems towing up Crestwood before the Acorn?
Fry

 

The small sensor wires can become coated with debris, usually small particles of oil-soaked dust either from road grime or through some lubricated air filtering systems.

Some electronics stores sell a spray that will clean them without touching the wires, but you need to make sure that it will not leave a residue.

Myself and some others have removed the sensor and cleaned the wires very carefully with alcohol and a Q-Tip...very gently.

 

Big n cheesy

easy brother your 06 3v V10 362HP 4.30 spinning tow monster better damned well clime brick walls with ease.. brother wallboyz is a 2v V10 310Hp version with 3.73:1. It should do much better then he is describing... I know some of the problem is the Carb state tune. Part is probably wrong brand or clean air mix fuel

Good service and tune up won't hurt but unless something is real wrong will not help that much either.

Ford does have a bad hobbit of using too many PCM codes and I know for a fact some V10s out there are just plain dogs... and if it is a suck *** code the only way to get a good one is to find a Ford master Tech who is wise, kind and knows what the hell he is doing

Before we go down that road lets have wallboyz do what he is already investigating... change out the fuel filter, clean the MAF, determine how old the spark plugs are and if over 60,000 replace them.

If you need to tow heavy and often you can cheat and find a set of 29 inch diameter tires.

Changing 3.73s to 4.10 or 4.30 is not a hard job for some one who has the tools and has done it once or twice but not for a beginner mechanic that is for sure! Paying to have them changed out can run $700 up to $2800 average around here for both front n rear is $1750

I suggest after we get the mechanical services done that searching for the right fuel be next... I have found myself that Ford motors can be real picky about brand of fuel...others here see zero difference.. but still there is a goodly amount of us who will swear that xyz brand sucks bananas and "MY" brand runs smooth as silk... here in central Texas "My" brand is Chevron with Techron... other around the country swear Texaco, or Exxon or what ever..

 

To clarify, I have the automatic tranny so when I say I downshift to 1st I do it the hard way. I am just now hitting 60,000miles. I did pullout plug #1 and it was burning clean with the correct gap, it was worn looking though. I don't relish changing those rear plugs as it gets tight deep in there. It looks like the fuel injector rail may come into play. I did buy the new fuel filter but after reading a blog about taking 3 hours to remove the old one I'll be waiting until this weekend. Especially with gas at $3.35 a gal!!

Fryzil, Crestwood is slow going as long as I'm moving. Get me stopped where you lose a lane or at the checkpoint....I crawl and have to work up momentum to get back to 30 mph. Boy, I' sure like to climb that friggin brick wall.

 

The fuel filter will take you under 30 min if you have problems.

 

3 hours for the fuel filter? no way man , 30 mins tops on your back in mudie water.spark plugs maybe 3 hours when you do them as art k and a few others have posted . as you most be carefull, useing never seize and the most use inch pound torqe wrench.
if the plug you removed was showing wear and the edges rounding off change them, use only motorcraft or autolight. non of the fancy costly after market cash wasters from other companies with multi this and that as they are a waste of cash and some of them even cause running problems.
change the fuel filter and you may not beleive how much better they run . fredvon4 has long been the preacher man here about causes of losees of power . one thing was the fuel filter. i myself started feeling a power lose. bingo as he is 99% of the time mine was cloging up after it was changed my power level returned. ck out my tech gallery about the new filter retainers for the 05/06's and look at what drained out after 20k of driving. esp with this new gas/grain mix fuel.
change the plugs also change the plug boots and use the specail electronics grease to help seal things up and ease reassembiling.
there is a lot to learn down here about self maintaining your truck and lots of us who always help each other out.
now a big note from me personally. if fredvon4 sayes something listen up big time. he is the man who has run a fleet of v10's of almost all years and found out a very large major list of things to do/not do and make life easier. monsta. art k our new moderator and a few others are the men who have written our self service book . i have have played the dyno games with a large number of after market bolt on products to see what really gives more hp.
skipper 'GRAY and v10kzz71s 'darryl" are our 2 super charger men gray as a whipple darryl a kenny bell unit. this is one of the real true ways of making hp .
rear end regearing and tranies i can help you with how to and highly say it's not back yard.
very soon we will have a new man named leveltenpat . pat is soon to be a site sponser and is the owner of levelten transmissions and level10power.he will be helping out with how to's on tranie and rear axle problems.
so please man open up. don't be affraid of asking ?'s . you have come to the correct place for helping out and saving money at the same time .

 

Charlie stop exaggerating

I am only right 81% of the time

There a quite a few in here with higher percentage... but that is a function of padded posts

something I would never do

(GRIN)

 

fred the information you gave me was 99% correct to me so thats my numbers if you feel less so be it man.
the performace drop when the filter starts clogging up was 100% dead on . big blue loves full pressure to the injectors

 

Hummm I think I will log another with a grin response to Charlie

GRIN