My speedo has not worked for quite a while, and I just took off the Gear Ratio Reducer and plugged the Vss in without the GRR, now my speedo works, but is off by about 15 mph. If I buy a new GRR will it fix the problem?

 

The VSS has already been replaced

 

It should
The GRR regulates the signal to the speedo, so that it reads correctly
Most tranny shops should be able to "build"a new GRRfor ya or repair yours

 

I've used these in the past in other Mopar products with no problems.

http://www.superlift.com/accessories/truspeed.asp

 

That sounds good, but the axle/gear ratio should not be different because I don't have a lift kit or anything

 

It is adjustable in either direction.
When you removed the speedo adapter it changed the speed of the sensor reading so the speedo thinks that either the tires changed size or the axle gears were changed.

 

Ok, that makes sense. I'm pretty much a novice when it comes to this kinda stuff, and your help is very much appreciated!

 

You're welcome.

 

There should be some numbers on the "GRR" telling you what the ratio is. The number varies truck to truck, so there is no one size fits all. I get mine from these people http://www.gilmoredist.com/ , they can make just about any ration you want in either a straight or 90° configuration.