What thread measurement do C3 shifter knobs have?

[C3RVETTE]

I have a stock TH350 auto. Is the shift knob using 1/2-20...9/16-20....5/8-18 threads? :confused Anyone?

 

[TJay]

Should be 5/8 NF (fine thread)

 

[C3RVETTE]

Should be 5/8 NF (fine thread)

Thanks! I've now heard 4 total measurements,but that ones come up the most. I called the place that carries these cool looking shift knobs today,& they said the same thing