Propane kits are relatively cheap, the big difference in systems is where the pressure is regulated at either at the tank or closer to the engine compartment. Be sure yours regulates closer to the tank, this reduces the higher pressure liquified propane in lines running under the truck.
I can say that I had a propane setup on a toy truck I had for a while IIRC it was a powershot 2000, (don't hold me to that) on a stock truck it was roughly the same as adding a good chip the diesel mileage went up however the $$/mile really didn't change when you add in the cost of propane. How much propane used depended on my right foot.
The reason that propane has fallen out of favor for these trucks is that it changes the timing of the combustion event. you now have fuel that is in the cylinder when it is compressing and it will combust prior to the fuel injection event from the direct injection cylinder. If you have a chip that is not listed on your profile you need to remove it or have it reprogrammed for propane usage.