Its a Leviton 5206 or Hubbell 7962 receptacle you need.either one will work.Leviton will be cheaper for you.

'.I just bought an older 3-prong oven to use for some light powder coating curing, but it uses what I think is the 10-50, which I think uses a hot/hot/neutral, and no ground.' = 10-50 is correct, yes.

I did a run using 6# wire, and ran all 4 wires, but only connected hot, hot, and ground since the 6-50 wiring setup doesn't use a neutral (based on my understanding).' = That's correct, no neutral needed for most smaller welders. 'So a few years back I installed a 50amp run so I could run my plasma cutter and welder in the garage. Sorry, not linking is a pain, and makes me understanding of electrical seem elementary (perhaps it is). I can't post links yet, otherwise I'd share photos of the outlet and dryer plug. If that's the case, I'd need to just do another outlet off an open circuit, right? If so, then dang, because running 6# wire is no fun. So perhaps I'm answering my own question here, but if my assumption is right that the 10-50 uses hot/hot/neutral, I can't use the same outlet and just change the oven plug, because then the neutral current would be running to ground, which is a no no. I just bought an older 3-prong oven to use for some light powder coating curing, but it uses what I think is the 10-50, which I think uses a hot/hot/neutral, and no ground.

I did a run using 6# wire, and ran all 4 wires, but only connected hot, hot, and ground since the 6-50 wiring setup doesn't use a neutral (based on my understanding). So a few years back I installed a 50amp run so I could run my plasma cutter and welder in the garage.

50 amp welder plug