This may sound odd, but the 1/4 inch is a pipe thread.  You can go to a home improvement or plumbing store and get a plug or drain there.

I believe it is an aftermarket four core, and I checked again without having ever found anything resembling a drain. Now I can balance the effort of removing it to have one installed at a red shop vrs. pulling the lower hose once in a while.

It's really unjujual for a raditater to NOT have a drain plug...that's really weird.
I don't know bout youse guys, but pullin the lower hose on the '74 is a major PITA!!

We just installed the SPAL dual fans and I really don't want to pull all of that this year. Maybe next year to remove the condensor would be a better time to take it in.

I'm with you, Joel--draining a radiator as part of a normal overall engine tuneup has always involved loosening a drain plug, not removing a hose. Having just replaced the upper and lower on the '78, that's not a job I'd want to have to do every time just to flush out the coolant.

Unfortunately, given the lousy location of the plug on this particular radiator (stuck under a flange on the support, thanks to some careless PO), I don't seem to have a choice.

Can't wait until I can afford a replacement from DeWitt!