I have a one-pipe system powered by a Peerless G-561-W-S, built in 1983 or earlier. My first DIY project was replacing my leaky wet return with a dry return in 2011. The following year I repiped the boiler, adding a 3" drop header.
Here's a picture of the original piping:
As you can see, it didn't have a true header. The pipe connecting the two risers allowed for equal distribution, but it did nothing to separate the water from the steam. Also, the lack of swing-arms was somewhat concerning.
Here's the re-pipe, before I insulated everything: