1988 Chevy C2500 Heater Core Replacement
 

Hi I'm Juan, I have an 1988 Chevy Pickup that needs a new heater core.
I have taken apart and pulled the old one out.
I am trying to figure out what the right heater core for my truck is.
I look online and it seems that I have two options for it.
One says "with A/C" and the other says "without A/C."
Can anyone tell me what the difference is?

And I apologize if this question has already been answered before.
I am new to this site and I tried searching already and couldn't find anything.