PRO2K,

Here is the link to the GE spec on your ballast. It is a 73 page PDF file but it shows all of the application and possible configurations that you can run that ballast. I believe I saw that it could run T12 farther back in the spec but mostly T8 are recommended.

http://www.gelighting.com/na/busines...58_ballast.pdf

Good Luck and may sure to post questions before firing it up :blob6: