Two Battery Compartments are a distinct possability; I just had the street side compartment put in by my local AS mechanic; I would not suggest that you try this yourself unless you have a sound grounding(pun intended)! in Automotive Electronics, as the second battery will have to be tied into the univolt. The factory will not sell to ship a battery compartment, you will have to go through an AS dealer, even if you have more knowledge of what you want than the dealer
They charged me $350.00 for a battery assay' and it was the wrong one, it took many weeks of arguementation befort the technical staff finally were called in to address the issue; turns out that the parts people did'nt know what they were talking about
: The final analysis is that the compartment is installed and functioning perfectly. Your biggest problem is securing the Battery Compartment Assy. for your particular year and model AS, Good Luck!!!
Bob Cornute, WBCCI 4953 & Vintage (first Year) 1977 International 31' Rear Bath (To P&S In September for a re-plasticote job!!!)