I have a 1967 Belvedere , it has a 1967 GTX Dash in it is it possible to put the under dash wiring harness in without removing the dash? Just the basics in the dash am radio heater and lights.

What do you mean by "removing the dash"? If you mean removing the instrument cluster, the radio, the ash tray, etc. from the dash frame, I'd say yes. You have to remove those components to get room to work. If you mean removing the entire dash frame, I'd say no, you wouldn't have to.

I am going to remove the items you mentioned and drop the column , there are no vents to the defroster either. I will get to it this week and let you know. Thanks for the reply.