Is the Rear window a slider or not? If it's a slider check to see if the window drains are plugged up or not.

Need to know if it's a factory rear slider, or fixed window with or without chrome trim to even find you the correct seal.

X2 on the Cargo lamp gasket if equipped.

Also check the cab seams where the rook of the cab meets the cab pillars coming down for cracks, especially in the front of the truck.

The proper way to reseal the windshield is to have it removed and a new seal put in. Most glass shops will do this for you. There is a 50/50 chance of breaking the windshield on removal if its old. I would be hesitent to use RTV myself as silicone can promote rust on unprotected metal, and the way it sounds you may need a heck of a lot of it up front along the top edge.

As for the dog dishes, I saw a few at the wrecker the other day. Those Ford Motor Company scripted caps were standard equipment and fit quite a few vehicles. Half ton F and E series mostly between 1973 and 1982.

 

Same truck but 3 speed with OD push down an up for reverse!