So on my Hall the previous owner had the rear tank marked as main and the front aux tank marked as generator ? I thought that was strange. I drove the vehicle on the main tank till it was almost empty and when I refilled it 18 gallons fit. I drove a few trips, it just seemed like the range was short for the tank. I know dual tanks a supposed to be around 40. I have the OG brochure and it says 39.8 gallons.I didn’t know exactly how much the front tank was as it was full when I bought it. So after using the main tank only I drove from Portland to Bend on the front tank, the only thing is the gauge does not work so I just wrote mileage and waited till I ran out of gas which I assumed would be on the way. Well it didn’t run out and I drove around Bend for days till I headed up to Mt.Bachelor and on the way up finally it’s stalled. I switched tanks and restarted it and was on my way. The next day I went to Fred Myers and filled it to see how much it took. It took 53 gallons !!!
I couldn’t believe it. So the front tank is the main and the rear tank is the aux, so I have like 70 gallons total. I ended up getting 429 miles in the mountains on the one tank. Not bad. I bet on flat terrain I could get closer to 500. So I have nearly a seven hundred mile range which is awesome. Plus I purchased two 5 gallon metal gas cans from Harbor Freight that I keep in the metal box on the bumper for just incase or even more range. Honestly the more I learn about this camper it looks the all the previous owners didn’t really care or try to upgrade the vehicle at all. Looks like it was meant for me haha.

Is the front tank in the same compartment as the batteries? Mine just has the one 50 gallon tank in front of the rear axle.

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Nick Taylor - Green & White 1974 Hall GTC.
www.NicksGarage.com == www.HallGTC.com == www.NicksTeardrop.com

I believe the 50 gallon tank runs parallel between the front and rear axle on the passenger side and the other tanks in the normal back location , I’ll post a picture.

I checked mine again and the 50 gallon tank is actually behind the axle. You can see the end of the leaf spring here.

_________________
Nick Taylor - Green & White 1974 Hall GTC.
www.NicksGarage.com == www.HallGTC.com == www.NicksTeardrop.com