The current replacement for this ballast would be for F32 T8 lamps. These would be the new energy efficient electronic replacements. The new lamps would be smaller in diameter but give the same amount of light. You will need to look closely at the wiring diagram on the ballast as it does wire differently, do not match color for color.
If your fixture has 2,3 or 4 lamps they do have single ballast replacements to cover these bulb counts.
Of course you can still use the same ballast and lamps as they are available.
Here is a link to Advanced Ballast it can supply any part numbers you may need.
If you need more help please ask here.