I just bought one of these two tube 16 watt fixtures
from R and P Carriages on eBay. I put it in the hall between the fridge (curbside) and microwave (streetside) in my Excella. Works very nicely. I like it better than the ThinLite that was there. They also carry longer fixtures with 15 watt tubes.
I have bought some single tube 8 watt fixtures from R and P before. Good people and prices. These lights are made by Progressive Dynamics, the same PD that makes converters.