Differential Swap

NRWhiteKnight · Aug 30, 2017

Complete Rear End Swap

Hello everyone,

My 03 Ram 1500 QC 2WD has a whine from the rear end. It has had this since I bought it and now I am looking to replace the differential. According to my build sheet, it had the 9.25 Corporate LD diff, 3:55 ratio. I haven't the tools or the place as I live in an apartment (though I might be able to "borrow" a place) to perform a rebuild and it might be less expensive to find a used diff to swap out.

What I am wondering is what year models will be, more or less, a direct swap? Does the "Corporate LD" mean it's limited slip?

HemiLonestar · Aug 31, 2017

No, LD = Light Duty (it's a 1500). Any 02 to 08 1500 9.25 with a 3.55 will be bolt in/plug and play. Since you have a 2wd, you could (if you wanted to) swap in a 3.92 for better acceleration/towing power.

NRWhiteKnight · Aug 31, 2017

Thanks for the reply, Hemi. Would an older rear end be the same, say out of a 2000 or 2001? Also, if I went with the 3.92, am I correct in presuming that a speedo calibration would be needed?

bulrid8 · Aug 31, 2017

Anything before 2002 will have drum brakes. You want to keep your disc brakes. Dealer can reprogram for the different gears.

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NRWhiteKnight · Aug 31, 2017

Thanks bul. I appreciate the info.

Jerseystyle · Aug 31, 2017

By swapping the diff, are you talking the whole axle or just the diff itself? Swapping diffs isn't as easy as just removing one and installing a new one. You need to know how to set up gears, ie pinion depth, bearing preload and backlash, etc.

Jerseystyle · Aug 31, 2017

HemiLonestar said:
No, LD = Light Duty (it's a 1500). Any 02 to 08 1500 9.25 with a 3.55 will be bolt in/plug and play. Since you have a 2wd, you could (if you wanted to) swap in a 3.92 for better acceleration/towing power.

Define "bolt in/plug and play"...

HemiLonestar · Aug 31, 2017

Jerseystyle said:
Define "bolt in/plug and play"...

Dunno if I can dumb that phrase down any more...will directly bolt in place of your existing rear with no modifications necessary. That work for ya?

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Jerseystyle · Aug 31, 2017

You can't just swap diffs, it doesn't work that way. Tolerances change from every axle. He'd still need to set up the gears properly which would require a lot more work. Not something you can do at an apartment parking lot...

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HemiLonestar · Aug 31, 2017

Jerseystyle said:
You can't just swap diffs, it doesn't work that way. Tolerances change from every axle. He'd still need to set up the gears properly which would require a lot more work. Not something you can do at an apartment parking lot...

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The WHOLE rear, dummy lol, flange to flange.

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Jerseystyle · Aug 31, 2017

That's why I asked the question of diff or whole axle.

Diff = Gear set/carrier

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HemiLonestar · Aug 31, 2017

Yes I know. I never said the word differential, but thank you for trying to show us how smart you are lol

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Jerseystyle · Sep 1, 2017

Actually the OP only mentioned "swapping diffs" and doing a "rebuild". And you yourself didn't specify the whole rear end. Not trying to have a ******* match, just want the OP To understand there's a huge difference. I appreciate your sarcasm though.... [emoji849]

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NRWhiteKnight · Sep 1, 2017

I apologize for any confusion. Yes, I meant the whole rear end assembly, housing and all, not just the carrier. And I can't do the change here at my apartment anyway as it's against the rules. It sucks, but I do understand the reasoning for the rule as well as I am sure the work would take at least a day to do, presuming I had everything I needed. lol

I am looking at cost, as well as I do not know of the proper type of shop to have the work performed if I wanted to have it rebuilt anyway. Would I take it to a trans shop for that? I spoke to one general service shop about 4 miles from me and they won't rebuild it. I may be able to get then to swap complete rear ends tho. End result is it may cost the same to swap the rear end as to rebuild, unless I do the swap myself.

Jerseystyle · Sep 1, 2017

If you're not looking to upgrade anything, the cheapest solution would be to figure out what's causing your whine and then go from there.

I'd start by popping the diff cover off, inspect and change fluid.

Then I'd jack up the rear and check for shaft play and play in the pinion as well. Could be bearings.

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Jerseystyle · Sep 1, 2017

Any off-road shop should be able to handle an axle swap or rebuild.

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Ali07 · Sep 28, 2020

bulrid8 said:
Anything before 2002 will have drum brakes. You want to keep your disc brakes. Dealer can reprogram for the different gears.

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I know this is a old thread, but if the dealer doesn’t reprogram for the different gears, can it cause the transmission to act funny? Especially in a 4wd?

bulrid8 · Sep 28, 2020

Ali07 said:
I know this is a old thread, but if the dealer doesn’t reprogram for the different gears, can it cause the transmission to act funny? Especially in a 4wd?

Older models would just affect speedo and cruise control. If 4wd, you can't change rear ratio, without doing the front too. Two different ratios would tear your transfer case apart, the first time you engage 4wd.

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Differential Swap

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