that is for 69 ......for 68 the numbers on the radiator support will match the order number on the fender tag or build sheet not the vin.
Without a fender tag or build sheet in 68, there is no way of detecting a re-body which is a problem that was remedied starting in 69 and up when the radiator support and hidden vins matched the last six of the vin number and where it was made.
as said, in the case of this car....if the vin is not starting with RM23 then its not a road runner and if there is no vin tag then there is no car there....legally speaking.