Broken bolts on Heater Box
 

Hi,

I have removed the heater box of my '72 Dodge Coronet (no AC) and broke off a few bolts: there are 3 black bolts sticking out of the firewall to which the fan/motor is mounted inside the box. These were completely fused and broke off immediately. The bolts are welded to a plate to which the fan motor is mounted (i hope my description is clear). Is this a common problem? And is it possible to fix this without having to weld new bolts in?

regards. Willem