I think no one would give you grief either way. This looks like a pre-production Blazer...note the bench seat. Regardless, we know we have examples of 69s with and without. I don't know what the rhyme or reason was to which truck got one and which one didn't. We decided to go without on ours because it's a relatively early truck and I've found documented trucks that are newer without. But date of manufacture may have nothing to do with it. Do what you want and it'll be right.
At least we know a little more about this than when we started.