I have an old warden king/crane Viking boiler

This is in Canada, right?

That may be the reason for the "Warden King". Typically, when an American company expanded outside its home country, the other country would require some form of local ownership. I remember a couple from a long time ago- Sears, Roebuck & Co. partnered with someone named Simpson and sold its products as Simpsons-Sears, and the old Easy appliance company partnered with someone named McClary and dubbed its gear McClary-Easy.

I have an old Canadian Ideal Fitter catalog somewhere. Ideal was a trademark of American Radiator Co. but in the Great White North, it was called Sirdar-Ideal. I'll have to dig that up.

We have the Beacon Boiler Reference books here on the site. I looked through the Crane listings and didn't see a Viking, but since that was made in Canada it's probably similar to something in the listing, but has a different model name. Take a look and see what you come up with:

https://www.heatinghelp.com/assets/documents/200.pdf