Pat,
I found a 1999 catalog online, it shows them still made in USA. 221 toe, 222 heel, 223 track, 211 comma, and the 207 looking at a match cover it appears to be a bowtie dolly.
Do you remember if yours was held with 4 screws? the holes look drilled on mine so I used a plastic washer that is painted to blend in a bit.
Still haven't did any research on Stream Line, having so much fun with Stiles, Herman, Medart, Barrett of St. Louis. I am awaiting the arrival of a Stiles Rollsemout! the precursor to the Stiles-Herman or Stiles-Medart fender roller.