Reply to "Autolite distributor info needed please."

The hose is connected to "vacuum retard", the other connection that is capped with a black rubber plug is the "vacuum advance". It appears your Pantera's engine was only using vacuum retard, that's not so good.

Swap the position of the hose, leave the previous hose connection open to atmosphere. Don't use the little rubber cap at all. The unused side of the advance/retard mechanism must be able to "breathe" otherwise nothing will move. That's probably why nothing moved when you applied suction to the hose. That also explains why the effects of vacuum retard upon the engine's performance were no worse than they were.

There's also a good chance that the rubber diaphragm in the advance/retard mechanism has hardened, making it inflexible, and has also cracked and is leaking ... or on the verge of doing so if it isn't already. The advance/retard mechanism is something to be replaced. Crane used to manufacture a nice adjustable advance mechanism for Ford distributors (no retard provision provided, none needed). I'm not sure whether or not its still available.

The advance plate should move very easily, but with age & heat cycles the grease becomes sticky and things become more difficult to move. The entire distributor needs to be cleaned, rebuilt, and re-greased with a light synthetic grease.