Finally Joe, its time for that 850 to move its feet!
Great solution for the sprocket, some black paint over that and you shouldnt see the washers, if you even care!
One thing i noticed when you screwing the bevelgear unit to the sideplate, you wont be able to mount it to the undercarrige.
Instead mount the plate first to the UC with the rollers and motors on the plate, then slide the bevelgear unit into the undercarrige, just slide it in, when it stops, turn the bevelgear so that the yokes lineup and attach to eachother then push the bevel unit full in and screw it to the undercarrige.
Its a very neat way how they did this, 4 screws and you can pull the bevel unit out, i have done it once out "on work" and its so easy.
Now you will finally get to use the model full out!