I did a 2000 ls1 conversion and everything works except when I put it in gear and I drive it wont shift and if I put it in any other gear it will drive. So basically it will not shift into any gear and stays in 1st

 

You need to hook up a high quality scanner that can see trans data. See if it's commanding a shift. If it is, you may have a bad shift solenoid or sticking valve in the valve body. If it's not commanding a shift, you have a tuning problem. Also make sure your vss works.

 

Got +12 volts on the pink power lead at trans? There are two pinks so be sure to check the corect one as only one should have power.