Sounds like a bit of confusion and mixing of different plants and years in the conversation
Fist I guess your car is too far gone to offer up what was originally applied to your car - the reason for the question
Without option gone we have to rely on other cars built the same plant around the same time - in your case March 68
So VINs in the 176xxx-191xxx range one would guess
So looking at my collection I found what I was expecting - red oxide from firewall forward and red oxide from firewall rearward like on the other years at NJ
Here are a couple of pictures from examples One durign the period and one right after that period
Hope this helps