This is FWIW, not an ad:
If anyone is looking for a cargo light assembly, Bronco Graveyard has a deal $42, and free shipping. Do not be alarmed by the free ship notice dated to 31 July, I tried it today, and got it to work for me.
Mine was in tender shape, and so, I could not pass up this deal. I went to the local Pick to look for one. Found many through 89, and found them all fragile.
At any rate, get on it if you are looking for one. Check out the pics on their site too. The assembly is not bad looking!
https://shop.broncograveyard.com/1980-1993-Ford-Pickup-Cargo-Lamp/productinfo/34995/
1980 Ford XLT F350
400 Engine (rebuilt to 406)
Holley 2300 500 CFM manual Choke Carb
Under Restore (1st time)