My sentiments exactly. I'm pretty sure the 1500 has trac-loc on the 3.92

Perhaps the 2500 & 3500 have Auburns.

 

I like Ran's idea, drop the rear end from whatever and ya no worries about setting it up.

 

I agree completely but it was $975 for the complete rear (with axles) or what I paid. I couldnt justify the add't cost. I would much rather have done it that way if $ wasnt an option.

 

The LSD's for our trucks are the Auburn type, that doesnt look like an Auburn that is why we need a side ways picture, and it has TRAC on the top so I bet its not,
any way some of the tools you will need are dial indictors, with adapters to set pinion depth, you can buy a kit with all you need,
and a side gear adjuster tool, or you can make this tool from a nut welded on a piece of round tubing with a socket welded on the other end, for torque measurements

Bearing Preload Torque and Ring Gear Backlash Adjustment


Use Wrench C-4164, or equivalent, to adjust each threaded adjuster inward until the differential bearing free-play is eliminated. Allow some ring gear backlash (approximately 0.01 in. or 0.25mm) between the ring and pinion gear.

Loosen the right-side, tighten the left-side threaded adjuster. Obtain backlash of 0.003-0.004 (0.076-0.102mm) with each adjuster tightened to 10 ft. lbs. (14 Nm).

Tighten the differential bearing cap bolts. On 9.25" diameter (100 ft. lbs.).

Use Wrench C-4164, or equivalent, to tighten the right-side threaded adjuster to 75 ft. lbs. Continue to tighten the right-side adjuster and seat bearing rollers until the torque remains constant at 75 ft. lbs.

Measure the ring gear backlash. If the backlash is not 0.006-0.008 in., continue increasing the torque at the right-side threaded adjuster until the specified backlash is obtained.

Tighten the left-side threaded adjuster until 75 ft. lbs. is indicated.
This is just the minimum ,I know there is more to it
here is the tool


here is an AUBURN LSD diff

 

Wow, you can get it new from Dodge for $1200.

 

Thanks for the great info, Bull. I'll grab the tools the I need and the shims/crush washer or master set. I've read that you initially turn in the adjusters an equal amount then begin to take measurements. I'll compare your write up to another I read and get right back to you.

Thanks again for all the assistance. Also, when I drop by the dealer to pick up my mats I'll ask about the diff.

 

Snap a picture of the rear end, ours has coil springs so there wont be any leaf perches,that will also tell you what year, although there is a flat spot just inboard of the coil spring base perch ,nothing goes there

 

where did you find that? you mean the whole deal?

 

Taking the truck (with the 3.21s) from Atlanta to Disney in Orlando this weekend. I'll see what kind of MPG I get, unladen. My guess is about 1-2mpg better than what the 3.92s would get. Either way, I'll keep track and post the results. Some folks, including me, are curious what the MPG changes to when stepping up that many revs.

Next weekend I'll do the diff swap.

 

Theoretically, due to decreased loading on the engine with 3.92 ratio; the MDS will be activated more often and for longer durations at cruise speeds and therefore result in close to equivalent MPG as the 3.21.