POT wired wrong??

And if you turn it all the way the other direction then set your cruise control it will accelerate til it it hit top speed - or nearly top.

You're supposed to adjust it about middle, go for a drive and see where your OD kicks in. Stop - turn it A LITTLE one way. Then try again. See if your OD kicks in later or earlier. That way you'll know which way is to increase kick-in speed and which way is to decrease.

Mine kicks in about 40. I leave it there all the time. If I want it kick in later, I just turn it off using the OD button on the gear shift lever....You did move the OD button to the gear shift lever didn't you??

Here's one way :

Let's Screw-Up Your Steering Column With A New Tachometer and Gear Shifter! - Dodge Diesel - Diesel Truck Resource Forums

Real handy when you're running a POT and want to drop out of OD - saves having to reach down to the dash.
Be careful with the pin, the rest is a breeze.