Thanks guys. Perhaps some reverse engineering is in order.
I've already had a good look through rebrickable & am intending on using the guide by 'Jurgen Krooshoop' to modify the Excavator.
I also have an idea about using a subframe for the 3 way tilt on the unimog, so that it isn't necessary to remove pins manually to change the direction of the tilt. (I noticed the pins after looking up some of the pics).
At some point in the future I'm planning to build crowkiller's Vampire GT. just got to order parts, but am looking to make it RC, so may need to adjust the height / depth.
Anyway I'll let you all get back to the unimog posts.