I am considering installing a Webasto furnace in my 310. They have three model sizes to choose from; 2000, 3500, and 5000. The 2000 puts out 7000 BTU on high. The 3500 puts out 12000 BTU on high. I am wondering if anyone has installed this type of diesel heater in a 310 and what size they chose. Also, where did you fit the furnace?Regards,ChrisHalifax