Help in identifying a couple channel 1 sets.

[Electronic M]

IIRC 1948 was the year ch1 was eliminated. There were a number of models from various makers that were made before and continued after the change. Early examples of the Motorola VT-71 had channel 1 and later revisions didn't...and we still call both VT-71. The same logic should apply to your sets...as long as model number is labeled and chassis appear to be built close to one of the schematic revisions.

Some makers had many chassis revisions over the production run. The Motorola VT-71 used the TS-4 chassis and there were officially revisions A-J of the chassis...some sets have been found with a mix of different revisions circuit changes so there were some undocumented versions too.