The guys at Conleff Plumbing Supply on Lafayette are awesome! They had exactly what I needed!
The guy didn’t even have to think about it. I said I needed a laundry drain trap and standpipe and showed him a picture of the existing fitting, and he went into the back and returned with the correct item almost immediately. He apologized that it was expensive at sixty bucks, and I suppose I should have pretended like I cared. Honestly though I was so happy to have the right part that I probably would have paid a hundred bucks for it without complaining.
Don’t tell the sales rep I said that.
You may notice that the stuff in this picture looks crooked. It is. The little pipe on the bottom is the water heater drain, so it’s sloped on purpose. The standpipe is tilted because the existing elbow is a little bit out of plumb, which is not on purpose but seeing as how it’s sixty years old and doesn’t leak I feel no need to try straightening it. The water will drain just fine and no one will ever see it behind the washing machine anyway.