Hatch cover needed for transom 2003 Gulfstream. Recommendations please. Thanks!

Same year, same model. I can take pics of mine if that's helpful, but I would be amazed if you could get a replacement for it, unless it's all custom ($$$). I would just get a heavy piece of star board cut to fit, with a finger hole to lift it up. The benefit (and I've seen this on other boats) is that you could use that as a bait prep board. That hatch isn't water tight, so I don't think you're losing anything in terms of performance or safety by not putting hinges on it.
 
Boat Outfitters should have it, check there website or just give them a call 866 633 7961 they are very helpful and I didn't think there prices were so bad
 
What happened to your old one...missing or damaged? I just one of mine repaired and painted by an auto body shop (my son's). Looks brand new.