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Discussion Starter #1
Guys, I seem to have been dumb enough to buy a truck with an open rear diff. This truck will not be used much for towing, but should see service in the snow on a regular basis, as well as a bit of off road use and a fair amount of dirt road use.

Its a 2004.5 Ram 3500 Laramie, with a 11.5" 3.73 rear end

When I bought the truck, the previous owner told me it had a limited slip rear end, and I did a burnout in a gravel parking lot that left two tracks. I thought I was good, but recently only had one wheel turning when I thought I should have two, and jacked the rear end up. One tire spins the opposite of the other, so I am now thinking it is definitely an open rear end.

Any suggestions on the best options, and possibly economic options for getting better traction?

Thanks in advance
 

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Discussion Starter #3
One thing someone could clarify for me, is their a problem buying a good aftermarket LSD and then adding a locker? I noticed a lot of new trucks come with the option of an open diff and a locker, or a LSD. Seems like both would be something to consider.
 

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Discussion Starter #4
Any idea what trucks had the lockers as factory equipment? Would checking with scrapers be an option? Thanks
 

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No Dodges of that era, or any up to current models had/have factory lockers that I'm aware of.
Make sure it doesn't have posi before going any further, most 3rd Gens do, in my experience.
idk how much work it would be to swap in the GM version of the AAM 11.5 axle, but I really like the G80 gov lock that's in most GM heavy duty pickups since the early 2000s.

Considering you'll spend $600-1000 at least in parts to upgrade an open diff truck to a LS or locker, finding a complete axle from another truck could be a more economical alternative.
But consider where you drive. You still have a 4x4, so do you need a posi rear axle or just want one?
 

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Don't mistake the wheels turning opposite direction for automatically being an open diff...very possible the clutch pack in there is well beyond used up and simply just needs rebuilt. Pop the diff cover off and see what you got before going any further.
 

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Mopars don’t have “posi”, they have a “sure grip”. I say that cause I’m a Mopar guy and people that aren’t always call it “posi”.

Anyway, the factory crap in the rear diff sucks! It’s a bad copy of the Detroit True Trac. I’m saving up for the Yukon clutch style sure grip, just like they had in the Dana 70/80’s. Much better, handle more hp/tq and you don’t need to ride the brake or engage the e-brake to make it work.
 

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Discussion Starter #8
Don't mistake the wheels turning opposite direction for automatically being an open diff...very possible the clutch pack in there is well beyond used up and simply just needs rebuilt. Pop the diff cover off and see what you got before going any further.
Thanks, that might save me some grief.

I cant get anything from a tag on the rear end, but the build sheet just listed the ratio at 3.73

Would it specify a LSD? This truck is a Laramie 4x4, hard to believe it wouldn't have one.

I was looking at the truetracs as they have good manners on road but are apparently reliable and work well off road. The ARB option looks good, but not as reliable and very expensive. I realize these are different routes, but both would give me additional traction and not cause problems on snow covered roads.
 

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Discussion Starter #9
Mopars don’t have “posi”, they have a “sure grip”. I say that cause I’m a Mopar guy and people that aren’t always call it “posi”.

Anyway, the factory crap in the rear diff sucks! It’s a bad copy of the Detroit True Trac. I’m saving up for the Yukon clutch style sure grip, just like they had in the Dana 70/80’s. Much better, handle more hp/tq and you don’t need to ride the brake or engage the e-brake to make it work.

Thanks. So you think the Yukon is a better route than the true trac? I thought the clutches might be more problematic over time. I don't know the price comparison and install time for both, how does that factor in?
 

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Mopar calls ther limited slip(locking diff) Anti-spin differential. Code on 2nd gen was DSA I think it stays that . Look on sticker, glove box sticker or the build sheet. Maybe just needs clutches and kit in yours.
They have always been available ordered with either Antispin or open diff. Probably even new ones , though it is a gear system now.
 

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The knock off that is in these trucks isn’t very good. The Detroit True Trac is way better but is more expensive than the Yukon clutch style sure grip.

The Yukon will last almost forever, as they came in the Dana 60’s back in the muscle car days also came in the 8 3/4 742 case. Do the clutches wear out, sure do, if your always smoking the tires. Drive like a civilized human being, your good to go.

I build rear ends quite often, narrowing them for Mopar B, E, and A bodies, from 8 3/4 to the Dana 60. If it’s not a clutch style then I use the Detroit True Trac. You can’t go wrong with either one. Although the clutch style sure grip requires an additive to the fluid and I prefer the Ford stuff, the True Trac doesn’t require it so you save a few bucks, but it costs more to start with.
 

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Thanks, that might save me some grief.

I cant get anything from a tag on the rear end, but the build sheet just listed the ratio at 3.73

Would it specify a LSD? This truck is a Laramie 4x4, hard to believe it wouldn't have one.

I was looking at the truetracs as they have good manners on road but are apparently reliable and work well off road. The ARB option looks good, but not as reliable and very expensive. I realize these are different routes, but both would give me additional traction and not cause problems on snow covered roads.
For a street/ tow rig machine I would say Truetrac all day long. Gear driven instead of using the standard clutch pack is pretty awesome, and there's no thinking required. Just drive.

ARB's are very reliable, but also require on board air. Every failure I've seen has been from an install error. IMHO, complete over kill for anything but a pure off road rig anyways. I would not want a locker engaged on a street vehicle in the snow. Years back, when I had my Jeep, I had a welded 14 bolt rear. It worked great 98% of the time, except for those times I was off camber on a side of a hill or whatnot. With both tires spinning 100% of the time, there's nothing to stop the chassis from sliding down the hill. An open diff rig would just spin a tire, but the one not moving would hold it in place. That said, the same thing could happen on a snow covered/ice covered road. A limited slip diff (regardless of type) will be less prone to having the rear end kick out on you. Fun if you're in a snow covered parking lot and want to do it on purpose, not fun if you're not wanting to get your truck sideways.
 

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Discussion Starter #13
Good info, thanks. I never thought about the potential issue in the snow on a side hill. It makes the true trac seem like the best option, but I guess is need to know what I have now to start with. I am going to run the VIN through the dealership, and drain the fluid and inspect this weekend.
 

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Discussion Starter #14
Dealership says it is an open diff... so I will keep looking at the true trac and alternatives to that type of upgrade
 

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Discussion Starter #15
I can get a rebuilt Yukon duratrac for half the price of a true trac, apparently now as new from supplier. Any reason I wouldn't consider this?
 

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Stay away from anything that has springs in it. They won’t last. Stick to the Detroit True Trac or Yukon clutch style sure grip.
 
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