I have a 66 300 dlx 2 dr pst I'll start restoring next spring, no motor or trans. Has 3 on the tree. What 3 spd came with it and what can I replace it with. Thanx PC.

It most likely came with an all-synchro Saginaw 3-speed, and if you want to retain the column shifter, that's pretty much the only transmission that will work, unless you find one of the fairly scarce Muncie 3-speeds.