The 106548 is a stamping, not a casting and is the engine motor unit number. The engine block casting number is behind the passenger side head and between head and firewall.
If you were to do a search on EBay for "Pontiac Block" you will be able to find descript pictures denoting the location of said casting number to alleviate speculation.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
