Originally Posted by dan-fox
OTOH, anything that you can't reach because it's between understorage and bus floor is likely pretty well protected from the weather.
And on the 3rd hand, I would be drilling blindly and don't know what is between the box and the floor.
No need to ruin anything if it's still working!
The current bolt hole would work in some cases. I would still primer the holes before bolting through.