If you are planning to fit LED flasher bulbs, check the flasher bulb wattage before fitting a new flasher relay.
I have previously fitted an ERLY3P to a car using standard bulbs and it worked perfectly.
On my new '1973' car I fitted LED flasher bulbs all round, including the repeater warning lamp on the dash to provide a cleaner, brighter light, along with a new ERLY3P flasher unit. Unfortunately the miniscule power load of the LED bulbs caused the lights to flash too fast.
I contacted CarBuilder who replaced the ERLY3P with an LEDERLY3P, which is the type that I should have ordered in the first place....
This works perfectly.