After recently completing my little bruder bulldozer conversion I decided to next have a try at making an excavator. I began with a Bruder 320 and began cutting plastic. I will post pictures below as I make progress. I am teaching myself how to 3d model using Fusion 360 (free) and then printing the parts on my 3d printer. I will be using modified servo motors for the tracks as well as for slewing. I ordered a magom hydraulic pump and I am going to attempt to make my own cylinders and valves when I get that far.
Mount for track motor.
Hub Adapter
All Glued together