Replacement fuel tanks
It is common practice to change the original fuel tank for an aluminum replacement.
This is usually a good opportunity to reposition it in the vehicle.
There is not a requirement for the tank to be foam filled although it is advisable.
The tank must be securely mounted and positioned away from heat sources etc.
A sight gauge is usually fitted to enable the content level to be viewed at a glance. Be careful of the sight glass material as it has a tendency to harden off and fracture with potential lethal consequences. This is especially relevant to vehicles that have the battery or spare wheel in close proximity to the tank.
Fuel Tank Filler
The filler if enclosed in the tank area must have a catchment bowl to collect any fuel that may be spilled when refueling. This must have a pipe attached to allow the fuel to exit from the vehicle. Also remember that the leak off hole must be at the lowest point.
The vent pipe must vent to the vehicle exterior also, it is advisable to form a pig tail with the pipe and also fit an anti/siphon valve. This is especially relevant if your world turns upside down.