What year is your Jeep? All that you need to do is purchase a $40 speedo gear and spend 5 minutes to install it. Buy the gear and I'll install it if you need help.
Shoot me a PM if you need more info as I don't check here often.
1998 Wrangler Sport: 4.0 with a 5 speed, 2 1/2" spring lift, 33" Duratracs, Warn winch, and few other things.