Taking an A/T from column shift to manual on the floor on a 72 Charger. Plan on ordering the column collars from Brewers but what is involved in getting the shifting mechanism off the steering column?

Disassembly of the top part of the column.

What about getting the shifter arm and tube off the column? Major surgery?

There are a lot of parts. Spring loaded horn switch contact, key light, flasher switch, blinker switch, ignition switch, steering wheel locking assembly, three screws holding the top barrel on... It's all pretty straight forward until you get down to the steering wheel lock gear and the little C ring that holds the lower barrel on at the bearing. I always take photos during disassembly. I believe there will be a roll pin in the shift selector arm. A factory service manual will help and is recommended. That C ring is a bear. A nice sharp hooked probe is handy to get it off without boogering things up. Actually I am thinking there are two. One for the gear and one for the cylinder.

Thanks. That sounds about like I was expecting. I do have a manual that has an exploded view and some steps but I think it has to be too abbreviated. I’m down to pulling the splined retainer which is very solid. Letting it soak a little then try again.

I used a '70s truck column for parts to convert my '73 Newport coulmn. It was fairly easy even though it required total disassembly.

Pull the whole column. Remove the top two collars, wiring, etc. At this point you should be able to remove the steering shaft tube from the bottom. Bottom collar is held in place onto the shift tube by an allen key set screw that connects it to the shift tube. Once disconnected the shift tube comes out same way as steering shaft tube. You will have an extra wire in your harness from the PRND2L selector light that is no longer needed, and can be removed by collapsing the tangs on the crimped connector inside the harness. I use a small jewelers screw driver or paper clip.
Do the aftermarket columns come with the return spring for the bottom collar? The factory floor shift collars from 71 and forward have a return spring that hooks into a small hole in the outer tube and the other end of the spring has a loop that connects it to the bottom collar. There's also a small rubber bumper that attaches to the bottom collar. There's also a spacer that presses into the outer tube that helps support the bottom collar.