When I remove the panel from under the dash on the passenger side I see a big black box. Is the heater core located inside this box? I took out all of the screws and it still did not want to come off. I assume there are some more screw at the top. Also next to this was a thin silver box. I assume this is the ECM?

 

the silver box is the computer...

did you remember to disconnect the heater hoses under the hood?

 

Yes, the heater core is in that box. You'll be able to remove the top screws a bit easier if you remove the speaker and feel around for them. A swivel bit helps.

 

The heater core has been bypassed for a few months now. So disconnecting them was not a factor. And thanks for the help on the computer location. I plan to add a chip in the next few weeks.
I also have a chromed dual snorkel to put on after I rearrange a few things in the engine compartment. Will probably do that second week in April while on vacation. After I get back from the Masters. I have practice round tickets this year. Should be fun.

 

Thanks for the tip on the top screws, Rez. I had the dash pad off but I did not remove the speakers. I will do that next time. Might as well replace them too.