3 speed automatic column to 3 speed manual column?

As Dartman mentioned, the center shaft is different between power and manual, but the other tube and guts are the same. so, if you find a manual shift column, but, with the wrong steering gear, just swap your old center shaft into the new column. Don't use a 903 transmission. They're junk. Use the 745. You'll also run into the fact that your crank is probably not drilled for a pilot bushing. You'll like have to hone the hole and machine down a bushing for it. When you get the transmission, try to get the bell housing and flywheel along with it so everything matches. Personally, going to all the trouble, I would just bite the bullet and put in a 4 speed, but, that's just me. I don't like 3-on-the-tree shifters. They are just too trouble prone. Good luck finding one that isn't worn out.