In her post,
When a Chalky isn't a Chalky, self-styled Breyer historian Andrea Gurdon writes that the grey Bucking Bronco was discontinued early and painted over into black ones. No white basecoat was added; the pieces were simply painted on top of the grey.
Clues to look for in the black Bucking Broncos are a bluish cast in the transitional areas of stockings and the bald face, and shorter stockings and smaller bald faces (which makes sense - they were trying to cover up all that grey paint.)
I have two black Bucking Broncos, and naturally I pulled them out and checked them for any signs of that over-painting. Lucky me - both fit the description.
She also mentioned that the Classic Arab Foal had undergone a similar repainting. I checked mine, too - I've always thought it had an odd paint job.
It was very hard to photograph, but if you look at the knee on the left front leg, you can see a black line where the black paint stopped very abruptly and not very cleanly.
There is a black paint smear on one hind leg, and some of the blue-grey tinge.
Some overspray on the other leg - another sign.
See the thick, black paint and how it looks like someone took a paintbrush and only tried to cover the paint, not edge it nicely? More evidence.
I'd say my Classic Arab Foal is also one that has seen a second coat of pain!