The headlight relay comes in 3 versions: 928 618 107 00,  .01, .02, .04, but also a 928.618.107.05 exists (seems from OEM producer WITTRIN)

Relay XXIII-XXIV (number might vary per MY) headlamp combi,

928.618.107.00 version is not listed in PET but presumably for 1978-1982 or even 1986

928 618 107 01 version is for 1987-1991(RHD)

928 618 107 02 version is for 1978-1982 and 1983-1986

928 618 107 04 version is for 1987-1995

928 618 107 05 version compatibility is unclear, but it seems to be replacement for 1978-1986 and worked for a 1980 model. 

Technical differences are yet unknown.