Where do you add transmission fluid on a 1966 cadillac?

1966 Cadillacs do not use automatic transmission fluid, they use a non-detergent type motor oil. To add transmission fluid, there are two holes under the transmission oil pan, one for adding and the other for draining. Lift up the vehicle until you can see both holes. There should be a large rubber plug on one of the holes, remove the plug and insert a funnel. Add transmission fluid until it starts dripping out of the other hole. Once the fluid starts dripping out, replace the plug and finish lifting up the vehicle.