found 2 340's

Dartnut said
From the serial numbers, they are both from fairly late build '71 model year cars built at Hamtramck.
So the actual casting date on the side of the blocks would probably be late '71 to early '72 as a guess.

If you find a 1972 casting with a 1971 VIN, it has been re-stamped since that would not be possible from the factory.

1969, 70 or 71 casting is possible for a '71 car, but never a '72 casting in a '71.