Jim, sorry but there is just not that much more to it. There are two height valves on each axle. There is one "adjustment" nut on each valve for a total of 4--don't know anything about/never seen a "third nut". Each nut is located on a bolt, that slides inside a slot in the valve's adjustment arm. You adjust one nut at a time--always forget whether moving the arm up or down in relation to the nut raised or lowers bag--but will be obvious once you attempt the adjustment--air rushes into bag is raising it; air rushes out, bag is lowered.
Rear axle is easy to gauge height based on measuring 7.5" from frame bottom to middle of weld seam across the axle. Front axle is more difficult as you need to secure a straight-edge to the top of axle to get a horizontal reference to measure the 10.31" [10 5/16]. May have to recheck first valve once the second valve on other side of axle has been adjusted.
For years, this is where I stopped the process--"assuming" that once heights were in spec, the weight distro was proper/balanced--wrong! Reference this and other recent posts, you need to continue with fine-tuning the heights if you what to balance the actual 4-corner weights. Repeated fine adjustments on a segmented scale with wide margins will eventually allow you to get the axles within 100-200lbs without substantially changing the height specs......Again, reconciling the cross-corner, front to back, weight differences is the most challenging part of the "fine-tuning" process....
PS--could see where buying the adjustable, threaded connecting rods suggested by Brett, could make the adjustment effort more precise.
2003 40' MDTS
Garden Ridge, Texas