Your DDS from the underside looks just like my early New Home. Is your second machine in the post about the same size as DDS, or is it larger?
I ask because I don't think your second machine is a New Home - its made by National, it looks very similar to NH on the top side, but is a bit larger and has the National tension release instead of the NH tension release.
I'm trying to find my picture of the two side by side - may be faster just to go take another LOL!!