Sold 1969 Camaro Big Block Fan Shrouds

[camaro cat]

Question. Is the difference between the assembly line version & OTC,those 3 ridges I see on the over the top rise on the top front of the one on the left? They have the same pn#, & date clock with a 68 in it. Am I missing something else? Mine is like the one on the right without the ridges and said to be an assembly line piece. But I did buy mine from my local Chevy dealer parts counter although a loooong time ago.

Thank you

Loren