Non-A/C Heater Box

I'm deleting the factory A/C in my car (REAL Hot Rods have no A/C. You just sweat....) and I need to know the interchange on A body heater boxes. I got one with my car 8 yrs. ago and just today I was able to hold it against the firewall to see what holes need to be filled it. It don't fit.... I now need a non-A/C heater box. The extra one I have has a rod with a hooked end to support it inside the r/s fresh air door. The one that came out of my car didn't have one. Plus the blower motor is MUCH smaller and doesn't fit my car. I didn't have my camera with me today so I'll post pics tomorrow.

Any input? :help: