Replacing heater core

There are 2 bolts on firewall under the hood. I think 2 on top of heater core. And 1 on the lower left side kind of hidden in the carpet..

There are the two bolts on the firewall that hold the AC dryer on the firewall. These also hold the heater box in place. Also there is one bolt on the bottoom of the heater unit near the transmission tunnel. There are also a few bolts that hold the box to the firewall on the inside along the bottom of the windshield. After removing these bolts you can slide the whole heater box assembly towards you to reveal the four bolts that hold the cover on the heater core box. I had to disconnect my AC lines at the dryer because it would not slide out (into car) with them still hooked up.