Maybe it is a lost science by now but I remember in Holland we used to run all kinds of vehicles that way. I drove a BMW where if you ran out of one fuel you could just flick a switch and start running on the other again. There must still be guys that did those conversions back in the 70s and 80s around. Over here in the US it was mostly City and County vehicles that were converted. If I remember right all you needed was some minor carburator work.


54 3100 with 235
62 flatbed dump C60 with 261