When I build a new Ram at the website, I can specify a 3.9 rear end with limited slip differential. If I leave the option at 3.55, it doesn't indicate limited slip or not. I assume that the stock 3.55 is limited slip. Am I right on this or wrong?

NC

 

Limited slip is an option with the 3.92 rear end. I don't believe it is available with the 3.55.

 

3.55 is not limited slip. Only the 3.92 is limited slip. I have the 3.55 and it is totally helpless when it gets a little slick....it just spins one tire and i'm forced to put it in 4wd for the littlest things.

 

Given how wet it is in Seattle, the lack of limited slip is kind of a bummer. How much will the 3.92 kill mileage?

NC

 

I wanted the 3.92, but I bought my truck off the lot and it has the 3.55 rear. I was under the assumption that it would not have limited slip. However, it will spin both rear tires. Very noticeable when I played in the snow.

 

If you drive like normal and don't floor it from every stop then the mileage difference should only be 2 mpg tops I would think. And yotaman your truck does not have a limited slip, it is the esp kicking in to stop just one wheel from spinning. My problem is that in the fall during our harvest I would have to put it in 4wd just to pull into some fields because the esp would kick in and start to pull power from the motor so I couldn't spin my tires enough to keep moving on flat ground. My dads superduty had no problem driving in the fields and he weighs another 3,000 pounds over my truck but he has a limited slip rear end. I will be putting an aftermarket limited slip in my truck this spring before we start planting.

 

i have a 3.55 and have not noticed any slip. i live i n washington too. i understand why a limited slip can be better but with the esp and 4 wd option i am not sure why it is needed outside of the better gear ratio for hauling.

 

Sounds good. Plus I can always add this option later.

For the NW guy, where did you buy your truck? How much under invoice should I expect to pay. I don't know if pricing can be discussed here so PM me if that helps. Is invoice minus incentives the best I can do? I hate negotiating at the dealer.

NC

 

I turned off ESP. Both tires spun every time I tried it. Not sure why, but they did.

 

i'm not doubting you...on snow with the esp off it will do that if you give it enough power. But lets say you are on the shoulder of a gravel road and you go to take off, then your tire in the grass on the shoulder will spin and the other one with more traction will not, then the esp kicks in and pulls power from the motor, this happens to me quite often out here in the country checking fields and it gets annoying. But you do have the open differential and not the limited slip.