For a 1968:
-Fender tag has SO#
-Body is stamped with SO# on trunk lip and radiator support
-Vin# on dash matches build sheet
-VIN# shows motor type and model
-buildsheet has SO# and VIN# and is the only true connection between the two.
-motor has vin# stamped at top of rear of motor near bellhousing
-trans has VIN# stamped