You are looking at a GM, new, never installed engine cylinder head bolt.
The GM part number is 1647217. It is a discontinued part. 
This will fit :

Cadillac

Allante

1993

  • 8 Cyl 4.6L

ALLANTE

Cadillac

Deville

1994-1999

  • 8 Cyl 4.6L

4 DOOR, DEVILLE, SLS, STS

Cadillac

Eldorado

1993-1999

  • 8 Cyl 4.6L

COMMERCIAL CHASSIS, ELDORADO

Cadillac

Seville

1993-1999

  • 8 Cyl 4.6L

4 DOOR, DEVILLE, SEVILLE, SLS, STS

Oldsmobile

Aurora

1995-1999

  • 8 Cyl 4.0L

4 DOOR, AURORA