That looks like a 3gal eas tank for a Classic with air bag suspension. If it is I have the same tank, mounts etc. I ditched oba system project for a 20lb co'2 tank setup . That eas tank was designed to hold a constant 140 psi for the life of the truck bolted to the frame rail. That tank was made in Ireland ,sticker is still on mine.
For a rtw truck Co2 wouldn't be very practical. Looks pretty neat the way you set it up.
Land Rover 127/130 double cab pickup x 2 ( one is for sale)
Land Rover 110 v8 project truck
Sankey trailer also a project