[JohnZ]

That transmission is out of a '66 Impala built at St. Louis, ID'd by the high VIN sequence number. St. Louis was the largest assembly plant in the U.S. in the 60's - had a 60 per hour Fisher Body-Chevrolet Impala/Caprice line, a 35 per hour truck line, and the Corvette plant, all on the same site. St. Louis was also the sole site for all of the Corvair-based forward-control light trucks (Corvan, Rampside, window van, etc.). I launched the '68 Corvette there in '67, and launched the '69 Impala/Caprice there in '68.