I am trying to remove a heater core from a 2000 GMC Jimmy, about 174,000 miles. I have taken the bolts out from the inside; steering wheel & dash board, I have removed the hoses, the bolt on the fire wall; by the heater core, and the other two bolts that are the " ghost bolts", behind the front passenger tire. I still can not remove the " black box" that holds the heater core. Is there another bolt that I am missing? Is there a way to completely remove the dash so that it is easier to get to? I am in dire need of some help. The heater core went out 12/23 and I am getting very frustrated with this. Please help.