This is the one I use. I don't believe it is American-made, but it seems to fit the style you're talking about (other than also not being an 'antique').
Lesters Upstate Sports :: Baseball & Softball :: Accessories (ball bags, brushes, indicators) :: 3-Ball, 2-Strike, 2-Out Metal Indicator w/Grooved Wheels
The B-S-O wheels are also notched, so that, once you get used to it, you don't have to look at it to track the count (insert 'blind ump' joke here?!
).
Regards,
Andrew