[Raymond S.]

I would take that to a lighting store or perhaps Loew's might have someone familiar/w it. Don't know if their not available any more because they do have some four pin bulbs on-line at some of the sites which specifically sell bulbs. If they are the same size is another matter. But my main concern is the ballast and matching it to which bulb is correct for it.
If you are limited on buying then you might want to set up one tank/w a new light fixture so they won't cost much for the bulbs.

 

[PlantedRich]

I feel the pain. Light bulbs seem like a really simple item but finding one that fits and a price I feel right is also one of the relly hard items for me. I found a coralife fixture real cheap with a used setup but finding a bulb was tough. One of the hangups was the four pin connector. Rather than spring for a new fixture, I could find the right bulb but 4 pin inline rather than what I wanted.
My only advise would be to do a really thorough search on the net for the right wattage and shape. Then If I don't find the right pin alignment, it becomes a DIY project.
I took a knife and split the wiring on my fixture so that they can be arranged square or inline to meet the bulbs I can find. Crude? Don't care if it fits the fixture and works fine.