First, mojavemama, yes your light can be remote ballasted. In fact from what I can see, it is basically identical to one the 2 models that I have and use.
For anyone considering doing this project, Please read my entire thread on Converting commercial HID lights to remote ballasts http://www.marijuanapassion.com/foru...ad.php?t=45696 and decide if you think you can handle it before proceeding further. If not do not be afraid to have an electrician do it. You can carry it into the shop, pay cash under a false name and carry it out if your nervous but pick a name at random out of the phone book so it is believable.
The first thing is to confirm the actual wattage of it. Please verify for me that the label states that it is a 400 watt Metal Halide like it looks like in the picture.
Make sure that it is running on 120v, which would surprise me because most commercial fixtures are wired for either 240 or higher voltage, and I think I see 4 wires coming out of the tube, a bare one, a green one, a white one and a black one. It may be already wired for 120v but I'd bet on 240V.
The first step is to straighten out all of the wire coming out of the tube. They don't have to be completely straight, just good enough to let you pull the tube by unscrewing the tube with either a pair of LARGE water pump type pliers or a pipe wrench. The tube is right hand thread so turn it counter-clockwise to remove it. If you already know that, great, if not I've covered my bases.
Once you have the tube removed, remove the cover plate on the little square box on top and try to gently work the wires out through the side opening until you can read the labels on the wires. Then post a list of which wires on the ballast are hooked to which wires that used to run through the tube and which ones have been blanked off by putting covers on the end.
That will let me figure out if it needs rewiring or just a cord attached.
Please post pictures so the rest of the people can watch what you do.
The thread is also live linked in my signature.
Good smoking.