Furthermore, i ask you another question:

are you sure that for cars built in 1970 with a 1971 model year it was not possible to exclude the M470 (regardless of whether or not the M471 code was included) ?
Maybe only for the 1971 constructions on the 1971 model year it was not possible...
This would also coincide with the fact of the change of direction of the FIA ​​homologations, of some rear parts no longer being made of aluminum (standard) and of the modification of the standard sports interior and extension of the rear seat, with standard comfort seats again and rear seats without extensions.