Firewall question...
 

So question for you guys, this is the inner firewall right behind the radio area on a 72 Blazer, does this look correct or is there a piece missing etc.?

TIA

Re: Firewall question...
 

Re: Firewall question...
 

Looks like something is fastened by glue/caulk or other means to provide a support for radio or something else. Maybe see a bolt hole still there for the stock speaker/rear radio support in the pic. Some Blazers had no speaker hole in dash. Radio speaker was mounted under heater, A/C controls. Cannot say which design is more common. Would bet under dash is more common.

Re: Firewall question...
 

Yeah, weird looks like an inner panel is missing?

Re: Firewall question...
 

This is true sir about the speaker. However the bracket would still get mounted to firewall regardless of speaker configuration as it holds the rear bracket for the radio. Original posters photo looks like cowl has rust issues and maybe why the area looks tampered with

Re: Firewall question...
 

I do believe the rear radio support bracket does get mounted to the missing firewall piece for both speaker locations, I would think it would be the same for trucks as well?
No cowl rust issues that I can tell, just a little surface patina that would be on the inside of any enclosed part of a Blazer. If I run across another 67-72 that's being parted out I will take a closer look and see if I can remove that piece.

Re: Firewall question...
 

Hmm, A previous owner did a TBI swap and put the computer on top of the radio, I wonder if they flattened that section to make room? Always fun trying to figure out what a PO did.