The K01 is a different system from the K02 and K03.
Instead of the spring tension rotating bar in the 2 and 3, the K01 has the clamp and bar in one and you need to loosen a screw, pull out the clamp, rotate it, put it back in, tighten the screw, then continue sharpening. This guy has several videos on the K01 system.
The 02 and 03 system are very similar. They both have the spring tensioned bar that you just push to turn around. The difference is on the rear of the unit where the post is for the height adjustment. On the K02 you loosen a screw and lift or lower the entire arm/angle gauge unit until you get it about where you want then use a finer threaded rod to tune it in. On the K03 it has a rack and pinion system where you turn a knob and it lifts and lowers the arm then you fine adjust using the threaded nut.
It is not a plate for the upgrade, it is just the rear portion which adds the rack and pinion system which is more expensive. I think he calls it the lifter arm?
The system itself is actually surprisingly light. If you order the base plate it then becomes very heavy.