Possible but highly unlikely. You probably have 2 ballasts (6 tube ballasts are pretty rare, 3 or 4 tube pretty common) and they are up in the top part of the box. Another option is to rewire the box to use these or similar: http://www.amazon.com/Ledwholesalers-LED-fluorescent-replacement-ballast/dp/B002P3FQI6 .Quote:
...The ballast.....is not there! There isn't even room for one. We are wondering if its possible that it was external?