My experience with J.C.Whitney started out with my first car a 1931 Model A Ford, J.C.Whitney was pretty much the only source for old Ford parts except for a Company called Ford Parts Obsolete.
At the time (early sixties) it was said you could pretty much build a complete Model A Ford from the parts available in the J.C.Whitney catalog. and by the way, I had the same experience with the "pot metal" parts, a wish bone connector cup that held the ball to the engine.