I have a 1980 W150 Power Wagon with 360/727. I've had the truck for over 4 yrs now and have had to replace the starter relay multiple times. I will lose all ignition and lights. Install a new relay and back on the road again.

Are relays made terribly crappy and this is a normal failure rate or do I have something more serious happening with my truck that is causing the relay failures?

Ive had lots of these trucks, and I have never replaced one. A gazillion voltage regulators and the starters themselves, but not a relay.

I've had a lot of these trucks also. I've replaced lots of different stuff on different trucks, but nothing stands out as being unusually high replacement parts, but some trucks had a fondness for a specific part that it liked to consume.
But my ownership of those trucks was many years ago. These days, replacement parts are not nearly as high quality as they were back then.

I have a collection of 3 headlight switches here, all bought about a year ago, from 3 different parts stores, all of them look the same, and all of them have a warped plastic board inside that allows them to make connections whenever they want, or don't want. So far, the 4th switch is still working, but I expect it too will need to be replaced at some point.
I might suggest maybe you can find an older relay that still works and see if your problem goes away. Gene

Can't be the relay because it has no connection to your problem. See your other post.