Doing a trans and shifter swap in my '56 wagon. A friend at work brought in an old red metalflake shifter knob he had in his stash. He "thought" I could use it... It looks tons better in the car then the aluminum T handle.
The only issue was it didn't fit. The shifter has a 1/2-20 thread and the new knob is 5/8-16. So! Into the machine shop I go! I used a 5/8" diameter aluminum cutoff and drilled and tapped one end for the shifter handle thread. 1/2-20.
I chucked the stock up in the lathe and cut the 5/8-16 thread. This pic was after the 3rd pass I think.
All done and another pic with a test nut threaded on.