i currently have the heater core removed from my 91. first off it is a labor intesive job you will have to remome the bolts that hold the dash in to you can gain access to the the core to pull it uot and down. the ac will have to be disconnected and re charged. if you have the new core it should take you the better part of a day to complete the job but as i found out a new heater core was 365 bucks and dealer item only that is the only true pain in the ass .