I looked through the Chevy engine code pages of my Hollander manual today but found nothing in numerical suffixes either....didn't really expect anything as it's somewhat weak on these but thought it may be worth a whirl? .
I wonder if Geo Z. has access to anything that may shed some light on these? .
Fran Preve of Tonawanda plant may have something too? . I've spoken and messaged w/ him a few times over the years....anyone in contact w/ him lately? .
What other codes do you have Keith? .
~ Pete