Hey guys, looking for some quick information that I couldn't seem to find through a few different Google searches.

My truck is a 1995 Ram 1500 2WD with the NV3500 transmission.

Just recently I changed out the ring & pinion gears in the Chrysler 9.25" rearend and now my speedometer is off.


So here is my question: what do I need to change in order to correct the speedometer calibration?

From what I can find, the 1995 Ram speedometer with the NV3500 uses a mechanical signal from the transmission, can anyone confirm this? And how can I figure out which speedometer gear I need?

 

Start here. Apparently, there are short, or long shaft drive gears..... Need to figure out which you have, and what color it is. (color may not even be important... as you are going to change it anyway......)

Select which you need, and on the page for them, there is a chart that will tell you which gear you need. So, order the right one, and then just swap it out.

 

Assuming your speedo was correct before the gear swap, the easiest way to do it is to take the original speedo gear out and see how many teeth it has. From there it's just a ratio between your indicated speed vs. GPS at any given time (highway for example), so

(new speedo gear teeth #) = (indicated speed) / (GPS speed) x (old speedo gear teeth #)