Your previous filter is mounted in a round shaft.
In this case, the connection does not matter. You need the Ego3 toploader. This is only plugged in and not screwed.
In this case, the connection is important as in the freestanding installation. In the next steps you need to choose the right connection.
Unfortunately, we do not have an EGO3 filter for this variant, which is installed in a few whirlpools.