Collector mag has a story this month about an LP powered 641. The owner talks about LP pumps being necessary up north to fill tractor tank etc.. I was raised on a ranch in Texas having everything LP (butane in those days), 2 9N's, 2 8N's, 2 jeeps, Dodge grain truck, MM baler. I never heard of nor saw an LP pump of any sort. Tanks were filled via tank pressure equalization only using a relief valve which let vapor escape until you saw liquid coming out then you unscrewed it, shut off main tank valve and you were done and ready to go with a full tractor tank. But, I haven't filled a propane tractor in many years.
So tell me, are there LP pumps up north due to temps? Is this a difference in propane and butane or just a temp thing?