Hello all. I have a 2004 f250 6.0 cc/sb with 6'' lift and 37'' toyos. After a fresh tranny install, I'm beginning to hear how hard the oversize tires are on the 5r110w with 3.73's. I recently rode in a bone stock motor 03, same size lift/tires, and it was as quick as mine with my upgraded exhaust, and SCT set on anarchy mode. For that reason, I'm inclined to believe I have 3.73's. I've run a search for the only number I could find on rear axle, the code shown is v423f. I found no results. I'd normally jack up the back end and count revolutions, but my jack is leaking fluid and won't hold truck up long enough to get stands shoved under it.

Google doesn't tell me for sure if v423f indicates a 3.73 or not. Worried because I will soon be pulling heavy loads in hilly environments. It will be a month or better before I have cash to upgrade, but I like to research best purchase long before I drop coin. Probably go with 4.11's or 4.30s depending on ya'lls recommendations. In my race car I've always run richmond gears. Who makes the best gear sets for these big pumpkins?

My limited slip is also weak, and will be replaced in a few months, regardless of gear ratio. I'll be searching the forums for a better option for when time comes, but if anyone cares to chime in with their recommendations on this thread I'm all ears. Have a detroit locker in my street/strip car, and really like it's power handling capabilities vs driveability. What have you had success/failure with? Truck will be towing frequently, off-road at times, and abused on street on occasion so I need something that works well in a variety of environments.

Thanks!

 

Pretty sure they are 3.73s. Im going with 4.30 Yukon gears to help out my trans but I also have 38s that are wide as hell. Ive already replaced a trans and put in a suncoast tq converter once don't wanna do it again.

 

I'll spare you the mathematics, but if you want the same performance your truck had before the 37s, get 4.30s. 4.11s for 35s, 4.56 for 38s. While 4.11s would help, 4.30s will make your speedo closer to your GPS ON 37s. Think of it this way, the 37s sped the truck up, skewing the speedo. The 4.30s will slow it down.

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Oh yeah, you have too many characters for you axle code. Look at the door tag, there will be an alpha numeric code that you can reference on line. At $600~$700 for a Detroit Locker, it may be worth the money to replace the clutches in the LSD in the truck. Unless of course you have a one wheel wonder out back like mine did. Not to be rude, but how do you know it has a factory LSD.

 

Read on the door jamb like Karl said, the axle code is right there and a simple google search will let you know what it is. Likely 3.73's, pretty much standard in these trucks unless you got some sort of tow package. 4.10s and even 4.30's were offered.