Gas plant for my RD8

Hello municipality, am superior in my RD8 year 2004 running 95000km to have a gas plant installed. Who of you drives an RD8 and has one installed, which brand, what is to be considered and what are the experiences? What kind of plant would you recommend? Furthermore, someone in Emsland knows a company installing the gas plants. Was with 2 Honda dealerships that do not do it anymore, it said no more for those.