How do you check transmission fluid 1966 mustang?

To check the Transmission Fluid in a 1966 Mustang, start the engine and let it warm up to operating temperature. With the engine running, locate the transmission dipstick, usually found near the back of the engine bay. Remove the dipstick, wipe it clean, reinsert it, and then pull it out again to check the fluid level. The fluid should ideally be in the designated range on the dipstick; if it’s low, add the appropriate type of transmission fluid through the dipstick tube.