Well, thats not a M113.....I should know, I practically lived out of one for 2 years in Germany...look at the road wheels and the raised hump on the roofline..I think it's an earlier M75. But yes, the auxillary heater was a sheer luxury....all our 113s had them, but they broke down all the time, and other guys from other companies would try to steal ours! If we had to be away from the track for a while in the field, we'd pull the igniter out of it and take it with us....yep, cold will make people desperate!