I don't know that this will directly help, but worth a shot. AC Delco is serious about not having counterfeit parts with their name on them. If it is an issue with Rock Auto switching boxes, maybe they will do something about it. From their site:
GLOBAL BRAND PROTECTION TEAM
If you suspect that the automotive parts you have purchased are counterfeit, please send an email to:
gm_global_brand_protection@gm.com
Be sure to include as much information as possible as well as pictures of the part and with the packaging you have purchased.
ALL PERSONAL INFORMATION WILL REMAIN STRICTLY CONFIDENTIAL.
Please save the part, the packaging, the invoice and the receipt until we contact you (if you choose to be contacted).
YOU SHOULD RECEIVE A RESPONSE WITHIN FIVE (5) BUSINESS DAYS.