I did this job on my last GT. I would suggest buying a new Dorman upper intake plenum while you're at it. The OEM one has a tendency to melt around the EGR inlet. If I remember right it was about $135 at Autozone. It has a fix for that problem so you don't fill your intake with coolant like mine did. PM me if you have any questions.

BTW, the Dorman plenum comes with all the gaskets you need except the lim one. Get that from GM.