you still have all kinds of a/c stuff behind the dash, and the box is an a/c designed heater box. I agree, get the a/c one. Here's your chance to remove all the under dash a/c stuff while that dash is out.
Yea go for the AC one, it still got all the a/c crap in the dash and one of the guys at advance auto said its bigger and if it overheated, it will cool quicker once u turn the heat on full blast.