[MD83driver]

Gord is correct, they are located at the height level of the throttle quadrant behind the instrument panel half way to the firewall. My P337H has a holder that takes 4 c cells, I believe an Energizer battery, E-93. Cessna SIL ME79-5 references the Cessna Service Kit 337-46A and it explains the installation of the new updated version of the battery holder. From what I gather, there was initially a different sized battery to do this job, but the kit installs 4 C cells.