rockers...quick question

[newbie88]

hi all. i just bought a set of GMPP rockers and noticed there was another series of numbers stamped below the ratio size. sorry for the dumb question but, what do these mean?
also, is it possible to determine if they have been used? i bought them off ebay and the seller claimed they were new but they didn't arrive in the original box?

 

[newbie88]

sorry guys but could anyone give me a clue here? thanks.

 

[redc4corvette]

They are new to you.

Should be a GM stamp and ratio stamp.