While I'm grateful for the 31 gallon fuel tank GM provided on my 2019 Express 3500 155 WB model I would really like the benefits of a larger tank especially when towing the travel trailer which cuts the range substantially. I'm not one for letting my tank get much past 1/4 when towing to leave me grace when trying to find a fuel station that easy to get into and out of. I doubt any aftermarket company makes a larger fuel tank for these vans but I started wondering if the larger factory fuel tank that comes in the Express Chassis Cab/Express 4500 could be installed into an Express 3500 extended model and use only factory parts, fuel lines etc. Has anybody experimented with this? There is plenty of room under the van for a larger tank but I wonder if the larger factory tank on the 4500 models is taller, longer or both.

 

The cab/chassis vans have the fuel tank at the rear between the frame rails. That is where your spare tire is and not a great spot for a rear impact on a passenger van. You could likely install it and double your fuel capacity.

2009 GMC 4500 Van Cutaway - Auto News - Truck Ternd

 

I would look at mounting a second factory tank on the right hand side. There may be room enough there, depending on the exhaust routing. The inlet will have to be run through a couple of elbows to position the filler behind the door opening, maybe the parts for a van with left side doors would work there.

With an extended, you could also consider a custom tank, either fabricated or using a 96-02 metal tank (buy a new one to cut and lengthen) as a start.

On the 4500 tank: As to location, lots of vehicles have had the tank there, including the previous generation of vans. And getting the spare out of there does you a favor should you ever need to use it. My guess however is that the tank is taller as most 4500 trucks use bodies that sit higher off the frame.

 

Good info. I don't believe I want to mess with relocating the spare. I didn't realize the 4500 had its tank in a different location. That makes sense though as when I was doing internet searches for this I kept finding Express replacement fuel tanks that were 55 gallon and were more square shaped than the long rectangular ones we have. I may have to look into custom fab something to add some range. Thanks for a the replies guys.

 

titan makes larger tanks for the pick ups. check them out.
TITAN Fuel Tanks - America's Leading High Capacity Tank Manufacturer

 

I know this thread is a year old, but I was curious if anyone has tried or heard of replacing the factory 31 gallon take with the factory 55 gallon tank.

https://www.gmpartsdirect.com/oem-pa...-tank-84164752

 

So has anyone tried this?
https://www.gmpartsdirect.com/oem-pa...-tank-84082483

 

I am also looking into this

what did you find with the ambulance gas tank?

has anyone added a second tank or a bigger tank?