What rear end is this?

Look at the bottom edge...it's a 9 1/4, probably from a '70s B or C body

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You're probably right, he didn't turn it over for me but did say that the motor that came out of the same car (which he says was a 72-74 Newport) was a 4006630-440, which looks like a later 440.

Which if it came out of a C-Body, it's probably way too wide to put into an A-body without a lot of work.