I thought this light would have a CWA ballast, but it turns out it's just a simple HX. Like the 125, this ballast's coils are arranged differently than most core/coil ballasts you see. Why is that?
This appears to have aluminum windings because they're light in color. The varnish is brown so if it were on copper windings they'd be a rich brown color (since the copper is already brownish). 120V HX, 240V reactor, and 120/240V CWA/CWI were the most common ballasts offered for MV fixtures back in te day. Anything else was probably a custom-order type thing.