Well, I hope the tracks will stay together... I've come this far
Here are some comparison pics with the Bruder D4. As you can see the outside to outside track width is about the same, tracks themselves are about the same width, the 650 H has a slightly longer track length and a wider blade.
Made some more progress, got the block milled to mount the servos, the blade lift working and now I sorting out where to put the electronics. These pc boards are from the servos, I had to take them apart to convert the drive servos to 360d rotation anyway, so I plan on mounting them below and inside the cab. Yup, the third one is for the blade lift servo, figured I'd do that one too. I used 2.2k resistors after removing the 5k pots which made them smaller footprint and easier to mount. I had to do the blade servo too, I messed up the pot taking this one apart, thankfully I had a spare one from the drive servos to replace it with. I'll line up 4 C cells in the lower half and put the power switch and charge jack just inside the cab door on the right side.
John