Found this thread when I was looking for how to change out my heater core. So figured I’d put in my two cents now that I’m done.
the dash doesnt need to come out. The only thing you need to remove is the access panel to the center console on the drivers side footwell. And the little plastic air guide in the drivers footwell. It’s held in my two star bits. You need to remove it to make sliding the heater core out easier.
I didn’t have to go into the engine bay for nothing other than to top off the coolant when I was done. After I removed the clamps connecting the heater core to the heater core hose set I just took a very thin flathead and used it to help pry them apart being careful to not damage the hoses as much as possible, they are aluminum so they will mar up.
be sure to have a towel laid down and be ready for coolant to be dumped everywhere. Overall it took about an hourish.