Here are the other Knockout owners
https://pinside.com/pinball/machine/knockout/owners

This is why I always take photos of each area before the tear down. Document everything.

The tall ones go anywhere the ball needs to go under, and under the slingshot plastics. All the rest should be shorties.

This is something you learn over time...it's really just common sense. However taking pics before you take anything apart is always a good idea...I still doing this after many years of taking these apart and putting them back together.

The post heights probably correspond with screw lengths and if they are below or through the plastics.

Interestingly if you look at this photo:
https://www.ipdb.org/showpic.pl?id=1392&picno=50409&zoom=1

There is a short and tall post side by side by kickout hole. Which means this person did not know which went where either.

Hey @sennap1, I presume you probably figured it out (or worked around it) by now -- but in case you or someone else needs it, since I just finished refurbishing mine, here is a list are where they go:

Technically, there are only 4 required, at the following locations.
-- 2 support the round plastic above the center kickout hole
-- 1 supports the long plastic on the left; it was two tall metal standoffs so you need the tall post here
-- 1 supports the long plastic on the right; it was two tall metal standoffs so you need the tall post here

NOTE: If you decide to swap out the other 11 with the standard posts (like I did), just be aware the screws are longer so they might start to poke through the bottom of the playfield. You can trim the tip off the end of the screws with bolt-cutters to prevent this.

The remaining 11 were at the following locations:
-- 2 supporting the arch/gate at the bottom end of Knockout alley
-- 2 each supporting the red rollover lane guides (8 total)
-- 1 supporting the other end of the arch/gate attached to the right-most red lane guide