Does anyone know the towing capacity of a '66 Elky with a 283 (4V) and a powerglide transmission?

Maybe you should post on the BS site. More people, better answers from those of your generation. However in my 5th gen owners manual, it says on tire placard on door "do not load your vehicle beyond the weight shown under the heading "Vehicle Capacity Wt."". That means combined weight of occupants and all cargo including luggage compartment, luggage rack load, trailer tongue load, and any other non factory installed items. So I guess if you know the capacity you can figure the rest easily. I do not happen to know my capacity- the info long gone. I really think you should go to BS. I've been waiting for some response from our region for quite a while. Good luck.