I assume this is compatible with the mega cab? Also what year is the truck that it was replaced on?The one thing mentioned was the condenser. The original style is junk IMHO. I switched to the parallel flow and my temps in the mid 90s are high 30*s at idle, getting even colder while driving at a higher RPM, just not sure how cold. Never measured anything but idle.
I don't have a megacab, but I get my quad cab so cold I have to take it off full cold (do have 5% tint though and a tinted windshield.)
I thought about the shut off to the heater core, but my temps are already so cold I don't see the point.