You were just one click away when you were on Mike Dailys website. Look at the conversion number one and the conversion number two. It allows you to replace the four pin with a readily available and readily replaceable three pin.
conversion number two adds a relay to retain the dash mounted signal indicator light
I retained the indicator light but did not add an additional relay. I used 3M diaper tap connectors to the appropriate wires coming out of the flasher harness. This required the use of two diode‘s, rewiring the two prong bulb holder, and a proper ground for which I repurposed the OEM orange relay wire, simply grounding it to the OEM relay panel - my reasoning being that grounding was the original purpose of the orange wire, anyhow 😉
Those four pin flashers are very difficult to locate. Very rarely have I seen any and they seem to range around $150-$200 each