R4 X-carriage rod friendly edition

There have been many complaints recently about gouges in the top X-rod in Prusa mk3 variants. My hypothesis is that the Prusa X-carriage tends to twist bearings slightly because of the combined cable tie/uneven clamp tension. This is very obvious when installing bushings in the top bearing pocket. 

I modded the R4 extruder carriage to include a full width bearing pocket and clamp for the top rod. It also wraps around the bearings, and won't require cable ties. This is experimental. I haven't tested it as I'm already running the BNBSX extruder (which has a full length top bearing pocket). You may need to undo the extruder from the carriage to some degree to get enough flex in the carriage to allow the bearings to be inserted.