The Stupid Axle Questions Thread

[df2x4]

Axle spline count question.

I am getting conflicting information and have not found a definitive answer. Planning on putting a new, better rear diff in my '99 Tahoe Z71. Some sources say 28 spline and some say 30 spline. I've gone through several vendors' sites and have found both to be true. I am trying to avoid pulling an axle just to check before ordering the diff and installation kit. I've never had trouble with other vehicles I've done this for, but my research hasn't given me a conclusive answer.

So...which is it...? The truck was built early in '99 in Mexico. Push-button 4wd. 3.73s. Tow Pkg. There are some codes on the housing, but nothing I have found that translates to determining spline count. Maybe I'm looking at the data wrong...

Assuming we're talking about the ten bolt housing that came in most 1500s, it's 30 spline. I believe the 28 spline version of the 8.5" 10 bolt was used in early (like pre-'88) trucks and passenger cars. Page 10 of the Eaton Differential Application Guide can confirm this for you.

http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128302.pdf

 

[Kyle89]

I'm assumi,g it would be safe to say I have a g80 considering I can get her to kick both tires now and then when i try... Guess I'm gonna have to pull the cover and do the pain in,the ass way to find my ratio glove box codes are gone

 

[letitsnow]

Can't you jack it up and see how many times the tires rotate when you turn the driveshaft 1 revolution?

 

[Kyle89]

Hmm cometary forgot about that knew I was forgetting something simple lol thanks

 

[Joe Dirte]

Been lookin for bout half hour n comin up empty. 14 bolt sf rear 4x4. Would those be in light duty 3/4 ton 4wd? Is there such a thing? Z71 a semi or just a 10bolt?

 

[df2x4]

Been lookin for bout half hour n comin up empty. 14 bolt sf rear 4x4. Would those be in light duty 3/4 ton 4wd? Is there such a thing? Z71 a semi or just a 10bolt?

Pretty much all the Z71s I've seen were 10 bolts. The 14 bolt SF can be found in 2500s and I believe some 1500 diesel trucks.

@Z71Hobbs Didn't your 1500 diesel come with a 14 bolt SF?

 

[Z71Hobbs]

Pretty much all the Z71s I've seen were 10 bolts. The 14 bolt SF can be found in 2500s and I believe some 1500 diesel trucks.

@Z71Hobbs Didn't your 1500 diesel come with a 14 bolt SF?

Yes. The 6.5 half tons came with it. It may have been an order option as well, I’d have to dig through the heritage docs to be sure. The 6 lug 2500 also came with the 14sf.

 

[thz71]

Been lookin for bout half hour n comin up empty. 14 bolt sf rear 4x4. Would those be in light duty 3/4 ton 4wd? Is there such a thing? Z71 a semi or just a 10bolt?

14 bolt sf 6 lug came in alot of half tons actually. It just had to be the f44 package. Not rare but not common either. And like said 6.5 trucks and 6 lug 2500s.

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[Kevin Vanover]

Post here if you have a simple question. This will help keep track of common info and reduce clutter.

I have a 1999 GMC Suburban K-1500 Id like to put a really solid top shelf rear end set up that matches up w/ around 500HP power plant that will tow, climb, Mud, all purpose and ultra dependable.

 

[1991GMCshortstepside]

Look for a 14 bolt. Depending on your tow load will depend if you go semi float or full float.