Marty, that is exactly what I thought - that the rear bumper guard delete was a 68 cost savings measure.
Just this morning I saw 7T01T202721 on ebay and it is looks to be a pretty decent original-ish car with no rear guards. But being a Phili DSO, depending on a lot of factors naturally (potential for rust), it might have been played with. The valence has no holes at the bottom.
I also see 7T01T122746 on ebay as well - and no rear bumper guards. This car had a shot of the trunk and it looks like some sealer was used (similar to the firewall heater hose holes on an AC car). Note the build sheet in the trunk also.
Maybe the gang in NJ had a thing against 6 cylinder cars and decided to delete them?
So in one day I've seen two of something I never expected to see. Time to play the lotto.