A CNG conversion for your truck is straightforward and will be similar in many ways to a propane conversion, just more expensive. You will need a CNG cylinder rather than a propane tank and a pressure regulator instead of a converter. CNG also has a significant power loss compared to gasoline but this shouldn't cause you to have any problems keeping up with traffic.
Because CNG is stored as a high pressure gas rather than as a liquid (in the case of propane), the cylinder won't be able to hold as much fuel. A cylinder only holds the equivalent of a few gallons of gasoline so you will either need to refuel more often or install more cylinders. The more you drive, the faster the payback.
