[utee05]

Yup that's pretty much exactly what is happening. It is a couple of inches outside the rails and it hits the rear mounts. The spacer was needed to clear them. To me it seemed to sit too low but I guess this is to be expected with any tank that is underneath the bed.

You couldn't see the tank from the bumper but it is clearly visible from the side. I assume there won't be any issues with it sitting that low? Also probably other gas tanks would fit in a similar fashion unless I go a custom route which would end up being expensive.