What's This K5 Blazer Widget?

[Bohemian]

Found this on the floor of my cab in my 82 K5 Blazer, after yanking all the carpet to rhino line or some kind of truck bed liner the floor from tailgate to firewall. I'm not sure wtf it is.
It's made out of rubber and it looks like some kind of plug but I don't know.

thanks in advance.

 

[8seater]

It's a firewall plug probably from right below where the hood latch cable feeds through.

 

[86454K30]

Its a plug that is in both lower corners of the firewall at the ledge where the floor pan meets the firewall. They "receive" the push ins that hold the carpet in.