I am seeing a 5 too, in which case this Fury was not born not red: ER6 was the code for C-body red in 1970 (FE5 is close, but I have not seen any FE5 Polara 'vert -- I know of all were ER6)Paint code looks kinda like R5.
Plymouth, yes. Fury, no: Scorch Red only, which is ER6. See the brochure at the ever useful fuselage.de:Auto Color Library does show Rallye Red F5 for Plymouth in 1970. 1970 Plymouth
I have asked the auctioneer for the tag and will post it when/if I get it.I would like to see a better picture of the tag. I don't see any sign that it was anything other than red. Underside of the hood looks original and red is coming through the black on the tag. Unless proven otherwise I'm going with it was red from the factory.