I changed my rear gear from a 3:55 to a 3:73 recently and now I need to get my speedometer working correctly. There is only a 2 mph change in speed which is no big deal but my odometer is off by about 30 miles per tank of gas. I need help with getting the right gear in my tranny that drives the speedo. Any suggestions on what I need to do to get this rolling would be great. Thanks in advance.
Mike

 

What year is your truck??

If you have a 97-98 then to really do it right you will have to pull the gear you now have and count the teeth (pulling the gear is very easy, maybe 10min job). Then go here
http://www.finer.com/Internet/pages/speedo.htm
and you can do the conversion for the exact gear you need.

 

superlift makes a excellent speed calabrater for gear and tire changes with two settings I changed to 4.10 gears and 35" tires speedo is right on.

 

Thanks, my truck is a 97. I plan to try something this weekend with the info you provided. If I run into any problems or have a question I hope you guys are still around