I know what this part is, but can’t find the part number that is on it anywhere online for a year range and such. I want to sell it is why I’m asking so I can give correct information.

Part number on the metal in the last picture is:

1213831

Thanks-

 

Looks like an energy absorber to me.

 

Aluminum '82-'84 Firebird front impact bar. Part # 10015310 for '82 and 10028371 for '83-'84. Fairly hard to find piece these days. Typically used on Cross-Fire Injection and L69 5.0L H.O. equipped cars.