Re-enlisting help, Any retention NCO?

Im in the army and will be deploying in 2 weeks, my window will be open when im in country, as per my unit retention office. Anyway, I want to re enlist, but I've been hearing stuff that the you can only re-enlist for certain MOS depending on your rank. does anyone around here know more details to this and prolly a website that has a list of the new rules. I want to get an idea onto what i can reenlist to prior to deploying