Did they ever produce a slant 6 4 speed with a console in 1966?

well, I used the guts from one of my early a-body sl/6 4spd Darts to convert my 66 B'cuda sl/6 3-on-the-tree to a Hurst-shifted 4spd on the floor. It wasn't all that much trouble to do, and it may seem like a "weird" thing to do, but it is a great combo in my opinion.
FWI: I believe the 66 4spd would have the "inland-type" shifter, which, IMO, though cooler looking, is a poorer shifter compared to the Hurst units.
Yep those Inland shifters weren't the best especially if you get a little rough with them. Sometime in it's life, mine was converted to a round stick Hurst. If I wanted to get nostalgic, Brewer makes an adapter to mate the Inland stick to the Hurst shifter. Best if both worlds.