San Jose, actual build date 11/2/66, 3rd member Casting Date 6K21, filler in axle housing.
On a side note, I find it amazing that there were only 12-days from when this 3rd member was cast, machined, assembled, freighted cross-continent, and out the end of the final assembly line of a vehicle.
On Edit: a few more images added. The pinion bearing housing has a date also, though yes...any example found MAY be a replacement, it stands to reason that if the date is consistent to the actual build date of the vehicle, that the main housing casting date would ( like my example) be much similar (within a few days).