Aloha Gary,
Commercial Lighting Supply (~2700 S. 900 W.) carries Fulham Workhorse ballasts and they are easily bought from online suppliers.
I have worked with Workhorse ballasts on more DIY and factory made lights than I can count.
There is a WH 3 and a WH 33 and they are pretty much interchangeable just different size/shape and different wire configurations.
Here is the Fulham spec sheet.
http://horse.fulham.com/specs-literature/specification-sheets/Here is the wiring diagrams page.
http://horse.fulham.com/contact-us/wiring-diagrams/Mark