To be fair, some applicants will submit valid conversions which are properly inspected and a certificate issued but later the bus owners modify the installation but do not resubmit the vehicle for inspection and recertification. The original certificate will specify the number of cylinders permitted.
What I don't understand in todays update is this:
Furthermore, some of the gas tanks were installed inside the bus,
Unlike trucks where the cylinders are usually racked externally behind the cab, with buses they are installed in the rear of the baggage compartment which is directly under the seating floor. Where would they be installed outside the bus? Has anyone seen external gas cylinders on a 'tour' bus?