I am looking for instructions on how to replace the heater core in my 1976 (1975 1/2) buick electra coupe. i have taken out the plastic dash and there is a black box that looks liek the vent control and to the left of it house the vacum components. whne i look through the vent doors i see the core but dont know what screws i need to remove it. The hayes manuel says i need to remove it from under the hood but the photos look way different than my car and the directions do too. can anyone help me with this?