[Rules] Transported units and stacking

[Shad]

Or there can be Three fully loaded transporters plus three combats in a hex?

This is correct.

It took me a while to find though. The allowance is hidden in the middle of Rule 4.3:

They are combat units, but they stack as transports, meaning up to three APCs and/or unarmed transports (plus loaded units) may stack in a hex with up to three friendly non-APC combat units.

So the maximum number of friendlies you can have in a hex is:

• 3 combat units +
  
• 3 transports +
  
• 3 more units being transported +
  
• unlimited leaders
  

Beware of bad things happening when a unit is forced to unload into an already maxed-out stack due to combat.