Differences in HVAC controls for A/C

[TimmyG]

I noticed today for the first time, that the HVAC control for the AC equipped 720 is different in more ways than just that little "A/C" light. The AC equipped controls says "Pull  A/C" and it appears to only have fan speeds 1, 2, 3. 

 

My truck's (non AC) HVAC controls look like this and has fan speeds 1, 2, 3, 4.

I never realized they had different number of fan speeds between the two control panels...? 

 

I previously owned an 86 ST with AC and remember the pull for AC function, but do not remember the fan speed difference. My truck does not currently allow me to pull the fan lever out slightly, as with the AC trucks.

 

Anyone know what I will have to change in the dash if I add AC? I have most of the under hood components already.