Packard Forum Index » Pre-War (1899-1942)

All,
My 'barn find' 1928 Packard has Champion C-4 plugs in it. They certainly look period correct but think they were also used in Fords so they might have been a plentiful and inexpensive replacement. They seem to work great in the car. I can't find in the Parts or Service book what particular plug was used from the factory in the 1928 Single Six. Does anybody have information on this?
Thanks,
Rob