I'm missing it all, jack and rod, mount, spring and anything else that is related like the lug wrench. Either the PO got rid of it all or it is yet another thing that GM left off my fleet truck. I do have a similar emergency marker kit shown in the spare mount picture and a three kerosene pot flare set that mounted to the side of the bed above the steps which GM also left off my truck.

59 GMC rare fleet option stepside pickup
57 Chevy sedan delivery
57 Ma Bell windowed panel (gone)
57 Ma Bell 150 sedan (gone)
57 Burb with p/s, Apache Res. school bus (gone)
56 Navy 3100 pickup (pieces)
56 windowed sedan delivery (US Dept. of Ag.) (gone)
55 Navy 150 sedan (gone) and many others now gone
Founding father Desert Classics 55-57 Chevy club now gone