Welcome to the job from hell. The heater core is behind the passenger dash. If you have allready removed the dash, you did the hard part. The heater core is covered and sealed in a black case. You have to remove all the screws, and squeeze out the front cover of the case. There are two attachments for the inlet and outlet of the heater core under the hood where the core exits the dash. You have to remove these hoses, and the pull the core out. The core may be screwed in. It is tricky to get out, but possible if you are creative. If you pulled the dash out and cant find it, you are probably looking at the cover of it, under and behind the glove box. Some screws for it may be tricky to get to, and you may have to thread a long screw driver through the radio, vent, cigarette lighter area to get to some of the " missing" screws.