I wonder if you have a particular question we might help with. Some code you are seeing that we might be able to decipher for you?
You were correct to contact the manufacturer's dealer rep to acquire the manual, it seems odd that it would take so long.
ALSO
Are your trucks equipped with Curtis controllers, if so, Curtis instruments has manuals for the controllers (which should include codes and wire schematics) on their web- site.
Search for "Curtis Instruments USA" should get you the code listing for these units.
AND
In my not all that humble opinion, if I had more than 2 units with Curtis controllers to care for, I would sure be wanting to have a Curtis handset. it makes troubleshooting and setup so much easier that it is well worth the $