Denny,
From what I've been able to discern, chrome ran out of production somewhere around the spring or summer of '51. Probably had a lot to do with what assy. plant had what in stock, etc. Then you've got dealer stock, so if a fella bought a new '52 and absolutely had to have chrome hub caps and bumpers I'm sure a dealer could have tracked down a set somewhere. I've never seen a corporate edict on the issue, but most agree it was sometime late in the '51 model year that chrome was switched to paint and the grill option was deleted.
Almost everyone goes for the chrome grill nowadays,(personally I've always favored the painted variety), but in reality I've come across very few trucks in 25 years of junkyard scrounging that were actually chromed, and that was just on pickups with the deluxe cab option.

Bob