[Nullifie]

On the LPG tank will be a cover made of aluminium that's fixed by a black knob, unscrew the knob and take off the cover. Then you will see a square brass part that's fixed with 4 screws. The middle of this part has a depression, and in that depression could be a meter that shows mechanicaly the % filling of the tank, then you could read how full the tank is. But it could be a electrical meter: reading this the electrical system of it has to work, and two possibilities could be: reading the filling with small LED at the switch-unit for LPG/Petrol, or if more sophisticated: the original fuel-gauge shows the LPG-filling then (but this system isn't used often). But a missing meter could also be possible. The surest test if there is LPG in the tank is by removing the brass piece and look if LPG comes out (see also my removal-description a few days ago, that in my opinion showed that removal of a LPG installation is a relatively straightforward process). If there isn't a leak I would espect to be LPG in it, but of course it could be that a previous owner bothered about LPG in the tank and already emptied it.