Ok i have a hanes manual but it isnt really helping on this. I need to put a heater core in my 78 150 4x4 without a/c. I remove the the little vent box right near the door but as far as the big black box that hold the heater core it doesnt have bolts. It looks like some sort of spline ot rivet holding it in. It hasnt been done afterwards . You can tell its factory done so i figure somebody has saw these before. It doesnt seem hard. I unhhoked the cable and blower motor too. I havnt unhooked the hoses yet cause i want to get into it first and be sure i can do it. My biggest fear is breaking my dash or the heater box.