I don't know about +4 but my 1980 +8 has just one relay for both. And it has failed a few times over the years.
I must admit Stephen the norm was to have one flasher relay to cover two 21 watt bulbs and another separately switched into circuit for Hazards, to cover twice the power of all four flashing. There was an alternative where two identical flasher relays were used dedicated to each side with hazard function parelleling them up.
As I said wiring info hazy for this year but only one flasher relay shown via GoMog
here. Preceeding diagram to 1989 also shows just one flasher.
