I am not sure it is for R17. I consulted P.R. 1002 covering R1313, R1316, R1317, R1323, R1326 and R1327 variants from 1972 to 1975. Perhaps it could be for later model years from 1975 to 1979 and if it is, then its is most definitely part of the emissions or exhaust gas recirculation or throttle body systems on fuel injected models.