340 Block Numbers

Hops this is the correct thread to post this, if not, mods please move it.
Question about different plant locations on my block. On the "date machined" pad on the drivers side below the head I show a "W" code meaning Windsor Ontario plant, but on the passenger side oil pan vin pad, I have a plant code "B", which unless Im wrong is Hamtramck Michigan. So.... could the block have been assembled in Michigan, but have had final machining in Windsor??
In case it matters, the engine is a 1969 block