'04 Hemi Quad Cab, 20 in wheels, completely stock with 78k miles on it. At around 70k miles this summer the pinion seal took a dump and started leaking fluid out. I was leaving for a fishing tournament and needed it fixed fast so I took it to a shop down the street instead of doing it myself. Needless to say, the truck has not been the same since. When I picked it up the guy told me it had metal shavings in it and that he needed to see it in a thousand miles to check the fluid and see what it looked like, so I asked for a sample of the old fluid so I could see what he was talking about. He smiled and went over to a bottle and showed me some nasty 80-90w that was chuncky with all kinds of stuff in it. Now I don't trust the guy at all because that was not my fluid. I had just changed the fluid at 50k and it looked good when I took it out then. Anyway, I drove it to work and pulling into my driveway the next day it made all kind of noise turning the corner and going up the incline. I took it back to him and asked him what fluid and additive he put in. He said Royal Purple and it didn't need an additive. I told him it did because it had a limited slip and he told me it didn't have a limited slip in it. I told him to put some in, so he did. I left the next morning to go to the tournament and it was better, but pulling the boat it still chatters when making a corner under load.
FYI, I tow a 24ft aluminum boat about 75% of my driving and my truck is paid for.

1) Do you think my lsd is shot and I need a new one or should I spend the money and put new fluid and additive in?

2) How much would 4.56 gears help me in towing at 65-70mph? 3.92's now

3) If I need a new lsd would you recommend the auburn or tru trac?

Thanks for your help guys.

3)

 

I'm not entirely savy on dodge rear ends but I had a 1999 dodge ram 1500 4x4 sport and I had what sounded like the same problem as you. The gears where all broke up into several pieces and everything seems ok just straight driving on the highway or anywhere else. But a soon as you turned the busted up gears would get into a bind and cause a vibration and they would make a grinding noise that you could hear. I'd bet thats what you've got. As far as gears go I'm not sure. You'll have to consider rpm range and fuel economy among other things to choose whats best for you.

 

Get your truck into a REAL shop and get that diff checked NOW!!!!

If you've got an LSD, and the infamous clips are coming apart--you could have catastrophic explosion/destruction. At least pop the cover and look for yourself

 

Thanks for the help guys. I will pop the cover and take a look at it this weekend. I know it has an LSD, so it looks like it may be kicking the bucket.

Is anybody running 4.56's in a stock truck with the 20inch wheels? If so, what do you think?

 

OK....Royal Purple does not need any additive in it. It's already inbuilt.
Second, that could have been your old oil he showed to you. If your clips or the gears are indeed "going", the oil will appear to be very dirty......trust me on that one!
If indeed he says you have metal shavings or as I call it "the sparklies" in the oil....it's one of the clutch pack retaining clips from the stock LSD cutting into your carrier. IF alowed to continue and it gets too bad, your looking at a complete new axle instead of just n Aurburn/DTT exchange in that baby.
You REALLY need to pop that cover and have a look see yourself if you don't trust anyone to do it for you. That's the only sure fire way of having peace of mind yourself.
It does indeed sound like the dreaded clips are starting to do damage.
As for the choice between an Aurburn and a DTT.....well I run a DTT as I had to replace my stock LSD for the retaining clip issues and the DTT is AWESOME!
Equally, there are many who have fitted an Aurburn and say the same, so your good either way IMHO.
But.....get this thing checked out URGENTLY and do no drive it if you can help it until it's sorted. You run a very real risk of thousands of $'s to repair it if these clips cut away at your carrier significantly. Do something now to save a lot of money. The old saying "a stich in time" never applied to something so well as in the case of the stock Dodge LSD's.
Al.

 

Ditto, don't pospone this.....