Here are a few pictures of the original E-1 distributor mounted on the truck, located on the passenger side of the engine block just behind the oil filter mount.
Here are two with the distributor cap on.
And one showing under the distributor cap.
I’ve found it really difficult to locate replacement parts for the E-1 distributor, and distributor caps, rotors, and points from the J13 distributor don’t seem to swap over. So I’m not planning to make any changes to the distributor before I get the truck running. Then I may try to do some updating.