There is a pin you can tap out of the lever and then you can grind a notch wherever you want/need it for whatever lever you end up with. The stub is specific to the trans (a R1 stub isn't supposed to work in a R1HD and vice versa) from what I have read. Shifters don't really care if you get into a pinch though.
Difference between a R2 and R1HD, the regular R1 is different yet. The pin goes in the slot, the wedge bolt engages into the big notch and is actually what holds the shifter from moving around.
How I made my chrome FX4 Level II shifter fit my R2 trans: