what tooth count do I need to correct my speedo? 36.5"-37" tires

Also, where is a good source for a speedo cable? The one I got from napa has been leaking from the crimp (t-case side) since new.

 

Drive gear tooth count (most likely 7) and rear gear ratio are needed the figure it out. Then you can plug the numbers into an online calculator. I'll post a link if I can find the one I've used in the past.

As far as the cable goes, I got one from Oreilly about 10 years ago and it's been just fine.

 

http://www.bgsoflex.com/speedo1.html

The speedo rev/mile is 1000. Remember that the gear inside the case is the drive gear and the one on the cable is the driven gear.

 

A big piece of the GOOD heat shrink with the glue on the inside works great for sealing tach and speedo cables - but you might have to pull it all the way out and slide it over the speedo end. Rubber electricians tape also works (wildlands fire engines can't have any "leaks" to pass inspection, had a few like this....)