my 73 shorty Qvan has been needing gas fill hose replaced for long time also wanted to swap out the standard tank somebody put back in it for the 45gal Hickey in my 74 doner Qvan. My bro inlaw helped me this week and we desided to go ahead with the swap as it was not as hard as we had thought.
I now have both tanks out but plan to take pics and measurements of the 45gal tank and have in recoated inside and painted outside b4 installing. this way others can try to have 1 welded up by a profesional since they are no longer made and it is a very strong steel tank well designed with thick 10 gage steel it seems and in very good condition inside and out besides a few dings from low ground objects hitting it over the 40 plus years of use. I will post pics and dimentions soon, as I know several have wanted this info b4.
As you already know, the 73 had one of those big gas tanks when I got it in 1974. There was a problem with the vent. The tube stuck down into the tank and when the tank was filled, it would start a syphon and gas would run out from under than van. This is not a good thing. I was told to drop the tank, pull the tube, and cut it off even with the tank. However, if the tank was over filled, this could still happen.
If it we me, I would not put that big tank in. As you said about your 74, the tank hangs down to low and gets hit off road. I got the 73 hung up on a rock because that tank hung down so low. There was a big dent but no leak.
I recently saw a 74 qvan long with saddle type tanks totaling 70 gallons. The tanks were high enough not to bottom out. If you want a lot of gas, this is the better way.
Unless you are planning some long trips in areas were gas stations are far apart, or long trips off road, there is no need for that much gas. That is about $150 to fill er up. I reccomend you stick with the stock tank.
Were you able to find a replacement fill tube?
the new fuels are harder on old style rubber than the arid dessert so bought all new hoses from automotive parts shop.
the vent prob is due to the charcol canister being low so i dont hook that vent anymore, just use the vent to vented lockin fill cap and the return line after fuel pump. and I am going to have an aditional LP gas saddle tank for 15-20 more gal since shortys dont have room for 30.
due to the rual areas having LP gas avail. not doing much off road in rocky areas so only thing to hit tank would be saplings. creeks and such I go in are wet crossings and tank slopes up towards bumper so dont think I will have any probs. also I looked inside tank with mirror and the 2 tubes on top are flush at top. only thing sticking inside is the center baffle to slow waves and the float for gauge. only design flaw I saw is the line out is at front left of tank so it wont get gas if low on fuel and that corner is uphill when running. I plan on doing most off roading using LP gas and reg for on road travel. the tank the guy in Iowa put on seemed to leak near fill but never found where. just swapped tanks in my vans while replacing hoses. also saw fill vent hose had loose splice. Missouri has more gas stations than dessert areas but not out in the woods and such and big differance in prices and operating hours from one to the next so at aprox 11MPG I want at least 300 miles worth and the stock 23gal tanks wont cut it. only thing is Ill need lots more octain boost and sea foam to keep gas from turning to water when not using lol.