Door lock Knob

[Black_72]

I am not sure this helps, but my factory '72 one is smooth on the stem with about a 1/2 inch diameter button at the top. I replaced them last year with a GM PART # 9813799 which was identical to my originals.

[jays 1971]

The ones that are installed on my dads 70SS are NOS parts. They were purchased from new from GM about 20 years ago. They have smooth sides with flared top end. Looks like the one on the right side of the pic.