Its a metric size thread on the stick. Its an M8 x 1.25 or 1.50. I can't for the life of me remember exactly.
I do remember buying a Hurst Universal metric shift handle and it didn't have the right size. I bought a tap and recut a thread in one of the adapters.

my car has had the gear stick cut down and is fairly thick, i bought a solid steel chrome skull knob for mine with light up eyes, and it slid straight on and all u do is tighten a grub screw into the side it comes with universal nylon bits so itll fit anything

It depends on how you cut it down.

Removing it from the gearbox, cutting the threaded end off it, then machining the end to a parallel diameter, and putting a thread on the new end would work fine. Most people just cut a section near the bottom (so the cut is hidden by the shifter boot) they then reweld the shortened end back on. This is less safe and not really recommended. I did this on my Stumpy skyline box and never had any problems. Remember to remove any nylon bits from the shifter before welding back together. Otherwise they will melt, and you'll need to find new ones.

As for shifting knob. Take your shifter with you when buying a new knob. That way you will be assured to buy the right one.

Chris.

mines been cut down, its not exactly legal as far as i know, most aftermarket, or some anyway, just slide over your stick and then you screw allen keys through the knob into the stick to hold it in place, and that way they fit all sticks

keep your mind above your belt!

Hey guys I'm new to the site. Just got a 1977 Datsun B210 as a project car. I was wondering since I dont like the shifter can I get a new one from like autozone or something. Maybe a hurst? Is there a certain size that I need? Also is it safe to cut the stock shifter down about 1" or are there aftermarket ones?

Thanks a lot everyone!