Replacing my heater core. (2000 Durango 4.7L) I've seen the vids & posts here. My 2 questions for this insane task are:

1. OEM part or aftermarket? Was looking at this part on Amazon:Spectra Premium 99341 Heater Core for Dodge Dakota

2. On a long trip when using the AC the directional vanes wouldn't let the cold air out of the box. The vent motor would be working but no cold air would be coming out. But once the Durango was shut down for a few hours it would go back to normal and actually blow out cool air from anywhere I wanted it to.

I want to order parts and have them here ahead of time so I want to know if there's anything else I need to replace to remedy this problem before I tear apart the dash?

Thanks

 

I got an even better question, how did you all get behind the transmission dipstick tube to get that last firewall nut? The tube is literally right in front of it! I can't even squeeze a 1/4" wrench behind it!