I am planning to redo my heater core and was wondering. Do I get to from inside the dash? The car has AC or do I get to from the casing that sticks out from the back passenger side  of the engine bay? I have the engine out.

From the dash side.  You have to remove the lower dash on the passenger side.  Also, you need to remove the hoses and the insulator (if still there) where they go up into the heater core from below.  When removing the bolts that hold the plenum divider (think that is what it is called), watch for one trick bolt that goes all the way through the firewall and has a nut on the outside (this one drove me crazy for awhile).  Be very careful pulling the heater core up and out.  The piping is soft and can break off if not handled gently or has a little too much corrosion.  Also get one of the gasket kits to put everything back together with (mine came from Zip).

If you search on this subject, somebody posted pictures and a description of the procedure a year or two ago and it is very helpful if you haven't been through it before. 

Good luck.

I'm with ya man. My pass. windshield fogged on me the other day. It did it again this morning. Looks like another winter project.

Hey I took the pad dash off and looks like I have to take the gage panel also. I tryed posting pictures and screwed that up. It looks more involved then just the dash pad.

Dave,

Check this out (click here) for a look at replacing the heater core in a '70.  This was in an old thread (found using the Search function) and posted by a former member.

Hey thats a good thread to have thanks. To take the Evaporator and blower housing from the engine bay are there bolts from inside the car to undo?

To be honest I don't know.  I don't have A/C on "The Toy" so I'd have to look at the AIM to see the detail.