If your pulling the whole heater box out from the interior you have to disconnect the two hoses going to the heater core in the engine compartment. then you have to unscrew the heater core nuts from the cover from inside the engine compartment and dont forget to watch for the heater blower tucked in behind the fender. The heater box should pull right out but the top of the box will still have heater vent connections. You can pull the insulation out wit hyour hands but will be very brittle and get all over.- since you have it stripped this far replace the heater core. better to replace it now than have anti-freeze all on your interior floor board. hope this helps but its pretty basic and easy.