Gen 3 vs Gen 4 Differential

Mradin

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I'm looking to increase the gear ratio on my Gen 3 (2003) from the stock 3.07 to 3.55.
While I'm at it, I figured I should also upgrade the LSDiff from the HydraLoc (std on Gen 3) to the beefier GKN Visco Lok (std on Gen 4) which I understand is a significant upgrade in performance & durability.
Did anyone out there do this?
Are there any other changes to the guts that I need to make to make sure it fits my Gen 3?
Lastly, can anyone recommend a shop that can do this work?
I figure my local mechanic can remove the unit and ship it out to have the work done.
If anyone out there has one already built that they're looking to sell, I'd consider that too.
Look fwd to your responses.
Thx
 

MoparMap

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I just did a straight gen 3 to gen 4 swap back in the day. The whole housing and everything is a direct replacement. But as Dan said, if you're wanting to swap gears while you're at it there are better options out there. I've heard nothing but good things about the Wavetrac over the years. I think the gen 5 unit uses different half shaft connections if I'm not mistaken (bolt on flanges instead of splined shafts), though it might be simple to convert, I'm not sure. You could always just put gen 5 half shafts on it as well I suppose if you went that route.
 

Viper Specialty

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I just did a straight gen 3 to gen 4 swap back in the day. The whole housing and everything is a direct replacement. But as Dan said, if you're wanting to swap gears while you're at it there are better options out there. I've heard nothing but good things about the Wavetrac over the years. I think the gen 5 unit uses different half shaft connections if I'm not mistaken (bolt on flanges instead of splined shafts), though it might be simple to convert, I'm not sure. You could always just put gen 5 half shafts on it as well I suppose if you went that route.
Yes, you are correct. You would need to either bring the G5 shafts along for the ride as well, or R&R the flanges and put G4 stubs in the unit for use on G3 shafts.

IMO... use the G5 shafts and upgrade the whole thing at once.
 

Steve M

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For those that don't do well without pics:

Gen 5 output stubs:
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Gen 5 axles:
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OEM Gen 5 axle bolts (sold in pairs) come with pre-applied Loctite, but I'd highly recommend drilling for safety wire as they have been known to walk their way out (usually when someone tries to reuse them without reapplying enough Loctite):
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Word of warning: supply on Gen 5 axles is drying up - they haven't been available from Mopar for a while. A few pop up on Ebay every once in a while, some in better shape than others. Probably worth a call to Calvo/Nth Moto/Prefix to see if they have some laying around from customers that are running 1k+ HP builds that required something a bit more stout. If they don't come with ABS tone rings, the rings from any Gen 3/4/5 axle are interchangeable (they are held in place by a light interference fit).

Similar supply story with the Gen 4 and 5 output stubs. Gen 4 stub shafts/axles are no longer available from Mopar, and last I checked, the Gen 5 stubs were heading the same direction.

As has already been stated, the Gen 4 and 5 differentials both used the GKN Visco Lok limited slip carrier. Due to that, the Gen 4 & 5 stubs are backwards/forwards compatible.

If you don't want to upgrade your axles to the Gen 5 units, the Gen 4 stubs (if you can find them) will allow you to use a Gen 4/5 GKN Visco Lok with your Gen 3 axles.

Good luck in your hunt...the parts are out there, but you'll have to do some legwork. I can help try to fill in the blanks if you run into issues.
 

Wanderer1

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I had a Wave Trac installed on my 2004 along with 3:55 gears at the Viper Exchange last year. Yeah 3:55 is where its at and really improved the drivability. The Wave Trac was big improvement i notice pretty quickly. Hard acceleration on a curvy on ramp i noticed, hard straight line aceeleration i noticed a difference all for the positve. I felt it was costly, is what it is. Nice to notice the difference in the car and not just the wallet. Hope this was helpful. Have a bitchin day
 

John Micciche

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I had a Wave Track and 3.55 gears installed in my 2008 about 6 months ago. My local mechanic removed the carrier and I sent it to JBM Offroad in Corona Ca. The Wavetrac is far superior to Visco-Lok, and the 3.55 gears make for a much better driving experience.
 

Gary Dawson

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I don't have a lot to add here but FYI, I just had my ring and pinion swapped from 3.07 to the 3.55 and it is definitely the way to go. 6th gear still only tachs 1500 at 70mph so I have actually began to use it occasionally lol
 

Viper Specialty

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For what its worth... anyone with a TR6060 should be sticking with 3.07, and changing 5/6 in the trans. Keeps 1-4 usable, and fixes 5/6 only.
 

MoparMap

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For what its worth... anyone with a TR6060 should be sticking with 3.07, and changing 5/6 in the trans. Keeps 1-4 usable, and fixes 5/6 only.

Isn't that possible on the T56 as well? I had thought someone made a retrofit kit that let you put the later 6060 style 5/6 ratios in the 56, but maybe I'm not remembering that right. I've thought about this more and more as I cruise on the highway in mine. I used to love the idea of cruising 70 at 1200 rpm, but the drone on my exhaust setup is pretty brutal right there. I can just pop it into 5th and it almost even becomes quiet, or I could cruise more like 80 in 6th and it gets more tolerable, but not sure many officers would like the excuse of "I can't hear when driving at 70" all that much. Swapping out the overdrives seems like it might be the best answer at this point. The last thing my car needs it any more torque off the line, so I've never really considered a rear end swap.
 

Viper Specialty

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Isn't that possible on the T56 as well? I had thought someone made a retrofit kit that let you put the later 6060 style 5/6 ratios in the 56, but maybe I'm not remembering that right. I've thought about this more and more as I cruise on the highway in mine. I used to love the idea of cruising 70 at 1200 rpm, but the drone on my exhaust setup is pretty brutal right there. I can just pop it into 5th and it almost even becomes quiet, or I could cruise more like 80 in 6th and it gets more tolerable, but not sure many officers would like the excuse of "I can't hear when driving at 70" all that much. Swapping out the overdrives seems like it might be the best answer at this point. The last thing my car needs it any more torque off the line, so I've never really considered a rear end swap.
Before I throttled back, someone was working on getting the 5/6 for the T56. No clue if it ever happened or not. It should be possible, but nobody was selling them back then.

The TR6060 gearsets I keep in stock.
 

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