You don't have to take the whole dash out. It helps to take out the passenger seat, though, so you have a place to lie on your back. Put a towel down so the seat studs don't stab your kidneys!
- take out the lower dash trim
- take out the cover on the HVAC box
- remove the cover on the heater core. There is one nut on the firewall where the floor bends up that is very hard to get to. I used a flex attachment on a nut driver
- go under the hood and remove the heater hoses
- replace the core
- refill coolant
- bleed system
I'm likely forgetting details. I belive book time is four hours. I did my first one in two and a half. It was cold out
