Dupont DOMESTIC books from 66-80
https://www.ebay.com/itm/115877327337?

PPG IMPORT from 66-68
https://www.ebay.com/itm/256066969460?

not to much PPG books sold. mostly Dupont books. a few RM and a couple of SW.

i didn't see much more on complete multiple years.
it seems individual years sell for $10-$20 each. generally the older it is the more it's worth