Hey guys, I have a 2002 QC 4.7L and I am thinking about adding an Auburn Limited Slip differential. My truck is 2wd and I have a 6" RC Suspension Lift with 35x12.5 BFG mud terrains with aftermarket 4.56 gears. I do a lot of hunting and take my truck off road for that and the weekend camping trips. Would I benefit from adding an LSD in the back or not?

I have the specs of my truck so you all could tell me if it would make a difference or not. Like I said the roads I take hunting are back on our lease property and rutted out but nothing too serious. I haven't gone back there after a decent rain and the last thing I wanna do is get stuck.

 

Of course you would. I know a lot of guys who have lifted 2WD trucks with aggressive tires and a quality LSD who get thru places guys with 4x4s, open diff and stock tires get stuck in.
Lot of south Georgia farm boys have a setup similar to yours. Around the farm/work trucks on weekdays, weekend hunting/fishing rigs...

 

Hey Lucius, how much of a power difference did the 4.56's make in your truck. My 35' tires have REALLY bogged down my truck.

 

Factory 3.73s I'm assuming? That's a heavy truck for a gas engine, 35's and 3.73s. I've been in a Mega with Hemi, 35s and factory 4.10s on quite a few occasions and it was wasn't terrible, but IMO 4.56s would give it a good bit more *****.

I wasn't pleased at all with my 1500 with the factory 3.92s when I went to 35s myself and went to 4.56s almost right away. Although I have my 1/2 ton pig weighing right up there with a Mega with all my sh*t...

 

Correct Hammer, 3.73's. Its not that bad around town, but when I tow is when it really shows. I was following my buddy who was pulling a 39' fifth wheel gear box loaded with goodies with his Duramax, I was pulling a Yamaha Rhino and a bed full of hunting gear, and I had a hard time keeping up with him on the inclines. Also, would 4.56's be good or would 4.88's be better.

 

The 4.56 gears made all of the difference in the world! My truck really slowed down and it felt like the engine was straining to get up to speed. Once I put them on its like driving stock tires back at normal height. Next to the lift its the best upgrade I have done. Strongly recommend it!!

 

Well, you'll never pull with a turbo'd diesel, doesn't matter what make it is or what you do.

I'm not aware of 4.88s for the AAM 10.5 rear or the 9.25 front for that matter, doesn't mean they don't exist, just I've never seen them. I'd say for a balance of day to day driving, towing, in-town and on the interstate, 4.56s would probably be the way to go anyway...

 

Hammer,

I am looking at the Auburn LSD for adding to my rear end of my truck. Pretty sure I have the 9.25 rear end? Also what is the difference between the limited slip with ABS or without?

Here is the site I was looking at. Which one of these would work?
http://www.4wheelparts.com/Drivetrai...rysler+9.25in.

Also would it be difficult to install since I already have the aftermarket 4.56's? I have a garage that is owned by a friend and they do most of my work for a very good price so I would probably have them do it.

 

For sure Hammer, I wasn't comparing trucks, my last truck was a turbo diesel, I was just saying he's pulling away from me pulling 17,000 lbs when I was only pulling 3,000.

 

Yep, you have the Chrysler Corporat (AAM) 9.25 rear. Same LSD I run. I bought the ABS unit since I have rear ABS. I wanna say I paid $350 for it in '05.

I had mine installed right with my 4.56 gears, wasn't charged any extra for the LSD install if I did it at the same time. I know the pin in the diff needs to be ground for it, but it also needed to be ground for the 4.56 gears, so you should be good to go...


I had a '91 Ford diesel, 7.3 IDI in the mid '90s, last of the naturally aspirated diesels and even without turbo, it'd out pull any gasser I've owned even with 4x the weight. Just a LOT of torque to work with in them non-spark plug engines. I didn't pull heavy with it, just a 3000 lb. bass-boat, but I bought it because I was racking up 25k miles a year fishing tournaments. For the weight of that boat and how aerodynamic it was, I might just as well had a bicycle in the bed, LOL.

The problem with the Hemi, in particular is it's a very "one engine fits all" V8 and as such, makes most of it's power WAY UP high in the RPM band. When pulling, you just can't get the RPMs up there into the powerband. IMO the weight of the Mega Cab alone is a bit much for 3.73 years, let alone towing or hauling with it. I'd have like to seen the Hemi version just come with 4.10s and leave the 3.73/4.10 option for the diesels. A turbo diesel has enough torque to pull moderate weight with 3.73s and would benefit a bit with highway fuel economy, not so a gasser. Gears will do wonders for getting the RPMs up nearer this engines "sweet spot"...