Gear shift knob thread size

[Lawson Cox]

I think it is 5/16x24, However, my hands are so shaky and my eyesight so poor, I can't be positive. I finally found a knob with the "H pattern" 1,2.3 R engraved on it but the thread sizes are different and I need to buy a barrel spacer to accommodate the differences.

I tried the search section but got no results.

Thanks in advance.

Lawson