This threaded replacement wand will require you to cut 8/32" fine threads in your original controller. Your OEM mirror controller is made of a very soft metal so one can often install these as "self tapping".
1967 and 1968 are different, see comparison picture. The 1968 version was rounded off due to new safety standards. The mirror nut tool will fit over the 1967 wand, but not the 1968.