I believe that on the 2005 supercharged SS, some engines were made with the series II block but had series III heads, while others had all series III parts. GM was reaching the bottom of the barrel for parts on the engine because they were looking to kill off the 3800...which they did.


"Also note that Series III engines are the base for any 3800 produced for the 2004 year and up. This means the same block, heads, & connecting rods apply to any remaining Series II engines made after 2004 also. The difference is that Series III engines received the new superchargers (Generation 5 - Eaton m90 - if equipped), intake manifolds, fuel systems, and electronics." (Source: Wikipedia.org)

 

I thought it was the L32 block instead of the L67, which really has no impact or change on anything.