any advice would be helpful in how to install a new heater core in my 1987 gt

 

This is a job u have to pull the dash and also all the way back to the console there are a lot of screws behind the dash that you probley wont put back in!Its your choice the heater core will be located behind the dash on the passenger side fire wall in a plastic container that container will have a lid on it you have to get the lid up get the heater core out and put another one in!