Just wanted to get some opinions on my plan to make sure I'm not missing anything as this is my first major project for the truck. I have a 2004.5 dually that I ordered a 60 gal. aux. tank w/tool box for. The truck has a tall fiberglass topper on it with sliding side windows.

It "appears" that I'll be able to turn the interior side of the sliding window assembly around so the slider is at the front end of the topper, right at the aux. fuel tank, so I can reach in for fueling and manual valve control. (One way or another, I'm going to reposition that sliding window.) Only drawback I see will be having to open the window from the inside. Also getting the valve kit for the filler tube. Fuel line will run through one of the pop-out plugs in the bed and the tank will be vented to the exterior.

It seems like a pretty straightforward installation. But I never saw anyone with an aux. tank under a topper and am hoping to avoid any surprise problems either way.

The OEM tank vent kit may be on the list later.

 

I think transfer flow makes a gascap that installs on the side of the topper... Dunno if thats what you are lookin for. As for the valve, after you check for leaks, just leave it open. I have a 95gal tank and leave it open all the time.

 

Thanks. I had considered the filler in the side of the topper, but was concerned that there wouldn't be much room for a neat and lockable installation with the length of the windows. That's why I plan to turn the window around for access through the slider. But I will check their website.

I haven't heard of anyone having a tank under a topper but figured that it has been done. I just want to make sure I'm not missing anything and open to any suggestions for a better installation.

 

I would put the filler in the topper to avoid a lot of frustration...It is a pain just going over the side of the bed... But I am kinda short. See if you can find one that is recessed so that the cap doesn't stick out and look bad.
ALSO... make sure you raise the vent in the tank above the filler cap level or you will have a leak if you fillerup!

Oilguy