Ah yeah I totally spaced on the year haha... It is a 99 K1500 Ext Cab
I looked closer and they are all 6 pin
I just found this:
You don't mention year or model of truck. For the 1998 K1500 the one in the drivers side footwell is the mode door which directs air to which vents depending on the vent selector. It's the easiest to replace. The blend door is on the coil box in the middle of the dash and determines what percentage of air goes through the heater coil and vaporization coil to adjust outlet air temperature. That one failed on me and it's not too bad but you have to drop the dash to get the actuator out. The last is the recirc door which is in the passenger side footwell. That one controls whether air is drawn from inside or outside the cabin and is supposedly a real pita to replace. The blend and recirc actuators I know are the same. The mode actuator I believe is a different part number.
So then it should be 3 pin by driver, then 6 and 6 on the air inlet door? I think?