The 5” rough country lift kit apparently doesn’t fit my ford Ranger fx4 because it has a 31 spline rear axle and not the 28 spline. Before I purchase thousands of dollars in rims and tires, does any body know this to be right? Some have suggested it’s just the U-bolt size which I can buy bigger ones, some have no clue. Has anyone done the 5” rough country lift with a 31 spline? Please help.

Welcome to the forum

The 2003-2007 FX4 Level II came with the Torsen 31-spline axles

In 2008 it was a Pay Extra option on the FX4, not included in the FX4 package, no Level IIs any more
So are you sure its 31-spline, not that it matters?

28-spline and 31-spline have same tube diameter, 3.25". and used same drive shafts and u-joints, internal axle bearings are different size
So not sure why any lift it that was for 2008 Ranger wouldn't work

Article here: https://www.therangerstation.com/tec...4x4-lift-kits/

5" Rough Country is there, no mention of 31-spline issues

everything I’ve read says the 28 spline is 2.75” diameter and 31 spline is 3.25” diameter. Also, my pumpkin has a tag on it that says “75w140 synth oil only” which I’ve read is 31 spline. I measured it around 3.5” so minus the undercoat it’s probably the 3.25”. And rough country’s website says otherwise about the 31 spline, so that’s weird that that website doesn’t say anything about it, I’m pretty sure it’s rare to be in my situation with this lol.
https://www.roughcountry.com/ford-su...ger-4wd-736988
down in the “notes-important”
also, when an off-road shop was trying to help me figure it out over the phone they gave ford my vin and my towing capacity is more than normal for an 08 ford Ranger fx4 stock. So that also leads me to believe it’s 31 spline. I’m not that car savvy, so I’m not sure if it’s a simple part to make the lift fit or not tbh. Also, I can’t find any lifts that are specify if they fit the 31 spline axle which I need to figure out before I buy 33” tires cuz those probably won’t fit stock lol. Thank you

Also, the fact that rough country’s website says that now about the 31 spline kind of confuses me because I’m a “needs to be perfect” type of guy. So I researched what rotor size I had just to double triple check it would fit, and somehow I didn’t see the “does not fit 31 spline” note? And the note splits 2 bullet points about the same thing, so my thoughts are my off-road mechanic was hounding them to find out, and then they realized it probably won’t fit with that exact lift kit package, so they changed it on the website. To scam me out of a refund if it doesn’t fit, just to warn customers? Idk but that suspicious because the website you sent me definitely just copied and pasted rough country’s notes, but now they’re different.

Sorry, yes, the 8.8" 28-spline is 2.8", 31-spline 3.25", tubes, so u-bolt size would matter

Just measure the length of the replacement u-bolts that don't fit, figure out your axle tube size, and then pick some up from RuffStuff. They'll be beefier than the junk that Rough Country sends out and you'll never have to worry about them.

So you guys think the U-bolts will be the only thing hindering it from fitting. Once I get bigger ones it’ll fit?

Yes, should be the only thing.