Relocating the tank is not a easy swap.
Full disclosure, I relocated my tank to the rear.
Disadvantages.
- Our trucks were engineered with the tank in the cab and relocating it requires a lot of changes, one of which is what to do with the filler. It was more work than I thought it would be. Since I was repainting the truck I chose to weld up the hole in the cab. Leaving a dummy tank fill is also an option.
- Managing the new fuel filler is difficult and can be intimidating. My tank came with a pop up filler, which I didn't use. They work fine with a wood floor but with the corrugations they are difficult to incorporate into the metal floors.
- Behind the marker light or tail light all require welding and fabrication skills not everyone has.
- Installing the fill behind the license plate typically requires a lower tank, can be problematic on lowered trucks.
- System changes, that are required for tank relocation, are expensive.
They do have several advantages.
- No more fuel in the cab. I consider this a safety item especially if the truck ends up on the drivers side where it could shear the filler.
- Adds weight to the very back where it does the most good for trucks with traction issues.
- Moving the pump inside the tank greatly reduces the noise if you have a EFI motor.
You have already stated you are going to replace/repair your in-cab tank. Which makes sense as it is the least expensive and certainly requires less effort and $ to fix rather than relocate.
Cheers.