the SX-42 (and its repackaged equivalent, the SX-28),

How did you come to the conclusion these were equivalent? Having owned and
restored both I am curious.

The SX-28 covered up to 43 mhz, the 42 up to 110mhz

The style was completely different

With the exception of the twin 6v6 audio output the tube lineup was
different (The 42 used many loctals instead of octals)

The tuning mechanisms were very different

Even the Hallicrafters logo changed with that model.

FWIW I would take a 28 over a 42 any day