Rear End Gurus Needed

[iconic_83]

I have 21 lariat 502a with a 8.8 3.31 rear end. I’m wanting to swap to the 97.5 rear end with 3.73 gears. Is this possible? Which 9.75 axle would I need? And what all would be needed to do the swap correctly?

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[12Lariat21]

Only difference I'm aware of is you'd need one from the same wheel base as you have, as the 6.5' crew cab has a 2-peice drive shaft and the rear end has a CV joint, where the 5.5' trucks have a single peice drive shaft with the typical U-joint on the rear axle.

 

[iconic_83]

Only difference I'm aware of is you'd need one from the same wheel base as you have, as the 6.5' crew cab has a 2-peice drive shaft and the rear end has a CV joint, where the 5.5' trucks have a single peice drive shaft with the typical U-joint on the rear axle.

id probably need to do the front as well correct? Wonder if it would be plug and play or if it would need any reprogramming

 

[12Lariat21]

id probably need to do the front as well correct? Wonder if it would be plug and play or if it would need any reprogramming

You would definatly need to change the ring and pinion to a 3.73 to match the rear. But I don't think the front axle is different...but I also don't know for sure.

Is there a reason you want the 9.75 axle? or do you just want 3.73 gearing? you can just change the ring and pinion gears in your current axle..

Also note, the Max Tow 9.75 axle has larger brakes on it, so depending on what wheel you have you may run into clearance issues. Provided you are looking at used/salvage parts. And I do believe you could swap the brakes out with your current axle...maybe...

 

[SALEEN961]

Why do you specifically want the 9.75" as opposed to a 3.73 Super 8.8"?

 

[iconic_83]

Why do you specifically want the 9.75" as opposed to a 3.73 Super 8.8"?

I think it would be a lot easier and maybe cheaper for me to find that rear end specifically and swap it out myself.

 

[iconic_83]

You would definatly need to change the ring and pinion to a 3.73 to match the rear. But I don't think the front axle is different...but I also don't know for sure.

Is there a reason you want the 9.75 axle? or do you just want 3.73 gearing? you can just change the ring and pinion gears in your current axle..

Also note, the Max Tow 9.75 axle has larger brakes on it, so depending on what wheel you have you may run into clearance issues. Provided you are looking at used/salvage parts. And I do believe you could swap the brakes out with your current axle...maybe...

Possible ease of swap. Instead of it being in the shop. Maybe save a little cash too

 

[ks54703]

https://www.car-part.com/

One can make the 8.8 a 3.73 gearing.

 

[SALEEN961]

I think it would be a lot easier and maybe cheaper for me to find that rear end specifically and swap it out myself.

Just keep in mind that swapping to the 9.75" will probably give you a larger pinion flange that won't bolt to your driveshaft. It can be made to work, but it's not a direct swap.

 

[iconic_83]

Just keep in mind that swapping to the 9.75" will probably give you a larger pinion flange that won't bolt to your driveshaft. It can be made to work, but it's not a direct swap.

Good info to know. Didn’t even think about that honestly. I think I could track one down as well.

 

[v8440]

The larger rearend may also put the pinion flange further forward than the 8.8 does, which would require a slightly shorter drive shaft.

 

[Captain Chaos]

Personally, I would just re gear the axles you have. Ring and pinion sets are cheaper than a whole axle

 

[jhelrey]

Or buy a different truck

 

[Dakar09]

You'll def need to match the front diff gearing. This sounds like it will get pretty expensive when all is said and done.

I honestly don't think the full axle swap is needed if you can get the geaeing you want in your current 8.8. It would just be ring & pinions front & rear, and everything else would bolt back up.

 

[EL5_Zero]

I've personally gone both routes with this mod on two different F-150's. Option 1, upgrade gears on existing axles and option 2 source axles from salvage yards with desired gears and do the installation myself.

Regearing stock axles at a competent shop was $1,650.00 back in 2020

Sourcing a 9.75 from salvage yard was $500.00 back in 2022. I did the install
Sourcing a 8.8 front diff from ebay was $280.00 back in 2022. I did the install

You can definitely save money, but you have to be mechanically inclined and have the tools to do so.

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