Exhaust Manifold ID

I bought this manifold a long time ago. I'm pretty sure it is for a big block A-body, but the part number doesn't show up in any reference materials I can find. Is it a factory replacement part? The part number is 2846729,casting date 2 5 71

2946729 = 1968-'69 LH A-body 383HP

not sure about a '71 casting date - got a better pic of the date?

I have had several 71 casting date big block A-Body manifolds, there was a bunch cast up on that date for replacements because of cracking in a couple of area and they had run out of replacement manifolds.

Thanks guys! Here is a closer picture of the date. Looks like i misread the PN the first time.

maybe some big block DEMONS were closer to production than thought ???