From the January 1972 parts catalog for Challenger:
3419878-9 1970, except F60x15" tires
3579380-1 1970, with F60-15" tires
3579380-1 1971, with F60-15" tires
3579624-5 Trans. Am, w/F60x14 tires
Thats verbatim out of the catalog. I know when I bought my fender from them in 1980 we were not sure which part number to order (1971 Challenger, non-R/T, 14" wheels, NOT a TransAm).
Barracudas have six different part number pairs; two for 1970 (depending on F60-15 tires), and four for 1971 (BH and BP, split between F60-15" tires and other) (BS, split between F60-15" tires, and other)