Hey, Members! New YJ owner, here, I was trying to upgrade my shifter-knob and broke off the knob!!! WTF! Any advice? Is there a product/hack out there that y'all can send my way? I guess I have to replace the whole component? Is just the 'stick' replaceable?
You can use a tap and dye kit to rethread the portion of the shift lever that remains. Of course it's going to be shorter now, so you may just be better off replacing the entire lever unless you're okay with losing an inch or so of height.
Buy a new shift lever off eBay, there will not be enough area left to add threads to the existing based on that pic. The shift lever gets thicker below the threads so adding threads is difficult.