Despite minor changes between the heat sink versions, the mounting holes are all the same (I know I have upgraded my two K1s through all versions of the heatsinks).
As I have them labeled:
In versions 1 & 2, the five parts are individual parts: Nozzle, heater, heatbreak, and blue PTFE tube between the heatbreak and the bottom of the extruder. Versions 1 to 2 heatsinks have some improvements to the cooling airflow. Half of the heatbreak and PTFE tube is within the heatsink.
Version 3 & 4 heatsinks the three parts are individual parts.
Unicorn (nozzle-heatbreak-metal tube), heater, heatsink. Version 3 has improved airflow over V1&2. Version 4 has improved heat transfer (silver fins are copper coated with, I think, nickel); black parts are structurally not cooling since they only contact the silver part are two screw mounts at the top.
