Must be pointed out that the best place to find this information is during dissembly and documentation of your car if it has not been striped in the past
If you lack this for some unfortunate situation then looking at other cars finished the same day and plant may provide the best guidance to go forward with
ok Jeff so the red oxide primer was still used in the forward area?
Vast, vast majority of cars built that year and plant
Batch gray was rearward under the vehicle then?
Approximately from the bottom or mid way in the transition of the firewall to floor rearward to just short of the rear cross member. Batch would represent what is more often found but as mentioned above there were periods of red oxide and and the tints and tone of later batch mixtures seem to be wider than earlier in the year.
Though I would post some pictures of both the more typical batch colors. Left off the odd ball colors that are less often seen so as to not confuse the subject or to suggest to someone viewing that they would be an "option" when painting their car
And examples of the red oxide
Just picked some examples of each that had a decent view of the color and tried to spread them across the months. Do have more of course