1964 Dodge Dart replace steering column seal
Here's an easy way to make an effective seal that's cheap and easy to install. Get a torsion bar dust boot, the original/rubber type. Cut it down 1 side so you can fit it over the steering shaft.. The small part of the dust boot is the perfect diameter to go around the steering shaft. The large part of the dust boot is perfect for going around, or against, the steering column tube. You can secure the dust boot to the steering shaft with a zip tie, hose clamp, or other device.
In addition, if needed, along the side that you cut to fit over the steering shaft, once fitted you can use some RTV or similar adhesive along the cut to close it.