Heater box swap

charger 2 said
Well what i had found was that the 73 up blower motors all had the 3 stud mounts , so i bought a box and brought it home and after some looking i drilled out the rivets holding the metal plate on, and put the 4 stud on
and it all looks factory ,

Thanks for that. I have a 4 std blower motor that works great and a good heater core. Now I just need to find a 73+ heater box.