I think TCI also do the smooth stainless caps, but it's been a long time since I looked.
Accessories like these have all but vanished now that beltlines have become so high.
The advent of spray in liners, and people who don't use a truck for work have changed the face of the aftermarket.
You might try putting a WTB post in the Marketplace.
David is pretty amazing in his bird dog like ability to find obscure stuff.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.