Dealers search for home CNG units by BRC (Phil)
http://www.brcfuelmaker.it/eng/casa/cerca.asp?click=no
read product decription below of what it does not include- like compressor, lines, tank, ect.. the cost is high to install this, but if you have a buisness that requires alot of running around then it would probally be a good investment- the guy told me that the CNG was only a 5 HP drop in the engines proformance- IMPCO designs waukesha engine carbuator parts and is very good quality.
http://www.afvcomponents.com/2011-chevrolet-1500-5-3l-v8-cng-bi-fuel-conversion-kit/