73 charcoal canister has a center top vent cap, 1/2" dia. & 3/8" dia. connection fitting on the top cover.

Does the 1/2" or 3/8" connect to the fuel tank vent?
and
Where would the other connection fitting connect?

 

Actually, it's 5/16". That's the one that goes to the tank. The larger one goes to the side of the air filter housing and the center one is a vent.

 

In this picture you can see the hose connected to the side of the air filter housing, just behind the air intake snorkle.

 

Is the air cleaner connection the one with the loose hose clamp?

The OE Carter 2150 carburetor has a 1/4" connection on the outside underside of the horn that connects to top side of the air horn.

Would tis connection be the same, if using a aftermarker open pleated air filter as the side connection on the OE air flter housing?

Most aftermarket air filter housings have punch out on the lower pan.

 

Believe n 1976 the carbon caniters have three connections, tank, carb, & purge.

 

You're asking about a '73, why bring the '76 into it? BTW '76s used the same canister. Its the square canisters that have purge valves.
Yes, the connection with the loose clamp is the one that goes to the air filter housing.

 

Was trying to understand the line routing on the carbon canister style with the "purge" connection and how it differs from the style with only the "tank" & carb" conections.

 

Gotcha. This is the canister that has a purge valve connection, the blue hose goes to the purge valve.

 

Found the OE air cleaner housing in storage for the 73 F250 390 V8.
It has the right side 1/2" hose fitting on the side just like your photo.
Now I know the purpose of this connection fitting.

Found a carbon canister on a 77 F150 V8. It has four rubber hose connections and a vacuum operated valve mounted on the top of the rectanglar shaped canister.

 

No such thing as a Carter 2150 carburetor. There is a Motorcraft 2150 2V carb, but it was introduced in 1975. 1973/74's came with the Motorcraft 2100 series 2V

Carter carbs were only used on 240/300's.

9D653 charcoal canisters: