The Corporate 14 bolt would not be original to a '68, they didn't come out until '73.
Some additional ways to ID what type of Dana it could be; On Dana and Spicer differentials, the series is cast on the housing, usually on top ofthe pinion snout, though I have seen some with the number cast on the left side of the case on the rear, next to the axle tube. Some wll also have the number stamped on the center of the cover, usually under the Dana/Spicer name and logo.
