[turbodiesel6_6]

I may be posting in the wrong place, so sorry in advance, but i have a 1998 3500 dually, 4X4 longbed 12V. I was just curious what ring and pinion is in the rear of these things? it has a 5 speed manual in the truck and it seems like it runs pretty hard at 65mph, like 2000 rpm. im pretty sure the truck has the stock size tires on it. Already did the kdp fix, is there any other issues that you can think of to let me know what to look for. Also..... every once in a while the speedo when taking off from a stop will ramp up to like 90mph and then come back down to speed, checked the speedo against gps and its like 5mph off. Any help would be welcomed, and thanks in advance!

 

[Dual K20s]

sounds like 4.10s to me.

As for the jumping gauge, the sensor might be going out or it could be a bad connection

 

[123buster]

in glove box should be a label telling what gears or the first three digits on the tag on the dif

 

[Dual K20s]

Mine doesn't say anything in the glovebox. It has a tag on the underside of the hood though

 

[turbodiesel6_6]

Mine has no tag in the Glovebox, i will check under the hood tomm. and see, any suggestions on the rpms? Seems like i would get better fuel mileage if it was runnin a little slower.

 

[Dual K20s]

I've got 3.54's in mine, and its perfect for high speed running or pulling a trailer in 4th, but with 35" tires I'd like a little deeper gear to keep me above 1800rpm more often. With stock tires I think 3.55's are great, 3.73s would be perfect for the best mix of towing and cruising.