Rear Axel Swap?

[TexProud]

Hi. I'm a longtime RAMForum reader, but first-time poster.

I found Part Number 68334756AG "AXLE ASSEMBLY. Rear Complete" of less than $1000 on MOPAR Overstock, but I have a few questions and am concerned about compatibility with my vehicle. I am hoping someone can help me with these before I order. My vehicle is a 2013 Ram 1500 Sport Crewcab 5.7L 4WD Transmission 8HP70. I cannot find any markings that give the gear ratio, but I believe it is 3.55. I called my local dealer, and they said my current axle is PN 68334752AG (3.55), over $5000.

My questions are as follows:

• How can I confirm the current gear ratio is 3.55?
• I see in the descriptions that the -756A is an "Anti-Spin Differential and -752AG is a "Conventional Differential". Is this the only difference between the two?
• I would prefer the anti-spin Diff anyway. Can the -756AG be used as a direct replacement for the -752AG? Would there be any issues with physical fitment or the function of the ABS, 4WD, or other systems?
• It looks like the axle is truly complete up to the brake mounts. Does the -756AG include the axle shafts, bearings, etc? At installation, is there any need to remove the cover or just add fluids? Is the diff already adjusted for pinion depth, pinion bearing preload, backlash, and carrier bearing preload?

I appreciate any advice as I am deciding between spending $2000 to have my rear axle rebuilt or buying this axle and replacing it myself.

 

[crash68]

Check the local auto salvage yards and www.car-part.com for an entire rear axle any 5 lug axle from a DS body trucks from 2011 - 2024 should bolt up.
If it's just the differential/gears that need to be replaced, consider upgrading to the TruTrac limited slip:

Detroit TruTrac Differential for 9.25ZF Rear Axle

Detroit TruTrac Differential for 9.25ZF Rear Axle

www.moes-performance.com

Surefire way to verify gearing, lift the rear end, put the truck in neutral and spin the tire one turn while counting how many times the driveshaft spins.

 

[TexProud]

Update... Thanks to GTYankee's advice on another thread, I was able to confirm my current 3.55 gear ratio, so that's a go. Just need to figure out the rest of the questions.

 

[TexProud]

Thanks Crash68. I checked on a used axle, and it was about the same cost as this new one. Go figure. I don't really have the tools or expertise to work on the gears (preload, lash, etc.), but if it's as simple as bolting up a new axle, that's no problem. I'm surprised the "Sport" model didn't come with the limited slip diff to begin with. Live and learn, I guess.

I've been chasing this rear end noise for a while. I replaced the U-joints, front drive shaft, and a rebuilt transfer case / shift motor, all myself, but it's still there. Finally spent $100 at the transmission shop for a diagnosis, and they said it was the rear end. They quoted $2300 to put a used axle in. Another shop agreed and said they could rebuild the diff / axle for around $2000. If I can bolt up a new MOPAR axle for $1000 or so, and add a limited slip diff, that'll be best.

 

[DanAR]

I don’t believe adding the limited slip will create any problems with the truck. It’s self contained in the axle.

 

[TexProud]

Thanks DanAR. That's what I was hoping.

 

[Bmags]

I just did this to mine last weekend, swapped an open 3.21 axle for a 3.21 AntiSpin. Took 5 hours by myself and I wasn't in a rush. Easy job with normal hand tools.

I picked up a low mile used one for $500... and sold my stock one for $600.

 

[TexProud]

Thanks Bmags. That's great. You wouldn't happen to know the PNs involved would you? Did everything bolt up correctly or were some modifications required?

 

[Bmags]

Bolted up just fine, no difference since it's all in the pumpkin. Externally they are the same housing.

I got mine from a salvage yard on car-part. Had them verify the build sheet showed AntiSpin. I don't know the actual part number.

 

[TexProud]

Sounds good. PNs wouldn't help anyway since we have different ratios, but it's good to know they are all the same externally. I'll check out car-parts.

BTW, I just noticed that I misspelled Axle in the thread subject. I guess I'm a little dyslexic on Thursdays.

 

[Wild one]

Sounds good. PNs wouldn't help anyway since we have different ratios, but it's good to know they are all the same externally. I'll check out car-parts.

BTW, I just noticed that I misspelled Axle in the thread subject. I guess I'm a little dyslexic on Thursdays.

Prior to 13 the abs sensors are in a differant spot,the early ZF diffs had the wheel sensors mounted on the front of the axle tube,in 13 they moved them to the rear of the axle tube. A few minutes with a die grinder and carbide bit,will make new notches,if you end up with an early ZF diff,other then that,it's a straight R&R job.If you have impact guns/tools and a floor jack it's pretty easy to swap either the front or rear diff on a 1500

 

[TexProud]

Great! Thanks for the info.

 

[Tominator223]

Sticker on pass side rear axle facing cab . Thats were they used to be. Tells pn & ratio. Not sure it overstock one has it.