Trying to remove heater core but can't seem to find any bolts or screws to drop it down off of firewall. I removed the battery box and no screws there. The bolts that hold the battery box on are right above and right below the heater housing but no screws holding heater box on. I can see looks like 2 sheetmetal screws through the hole where the squirrel cage goes but looks like they are put in through the firewall from engine compartment. But no heads on that side. Need help. Mine is leaking