If you don't have any documentation of the original tires, either Goodyear or Firestone would be acceptable for F70 x 14's. Chrysler had contracts with both companies. My 69 383 RR which I bought new Sept 8, 1969 had Firestones with the red side walls (redlines). My fraternity brother's had Goodyears. I always thought that Goodyear was more common on the Plymouths than the Firestones. In my opinion, the Goodyears look better.