Anybody know where to go to get good instructions for installing heater cores? Especially the heater box seals. I bought a sealer kit but not sure where all the pieces go. Thanks for any input.

 

AIM manual is a great source.. Once you have the heater box out it becomes unclear where anything goes... Once you think you have it then you don't and it fits different ways... I don't know if 68 and 67 are the same... I have the 68 AIM...

 

Very simular. I have done it in a couple hours.
Drain coolant from hoses, disconnect from nipples,
remove the five nuts and remove glovebox,
lay down plastic from beneath the heater, up the tunnel, to the seat, and over the rocker panel - use duct tape.
Pull out heater box - you can leave the cables attached, might have to unplug the resistor block.
Use 5/16 socket and remove clip, remove/replace core.
I used clay weatherstripping for a sealant between heater box and firewall.
Or you could use foam weatherstripping. - I had clay on the garage shelf.
Reassemble in reverse order.