With your 73 being a 400, would the gear ratio be 3:21 with the tag, not the common 3:23 in the 8:75, I mean don't the 9:25 and 9:75 look the same , The white books don't have any c body axle codes.
What's code on the tube vent? perhaps cheap out and install a window, in Wisconsin, they have to be wrapped with insulation LOL or really cheap, leave the door open and a can of freshener
so, I understand, remove everything, leave the column, leave the windshield, smush the glovebox, what did you do about the screws under the windshield gasket? I'm about to tackle my dash pad replacement, 68 polara