[morzh]

This type chassis with its very characteristic look was used in those radios that came before 20, including their first superhet, the 111/112.
The 20 had smaller chassis that was the first Baby-grand and would fit in a cathedral tabletop. The previous one would not; the only tabletop it would fit into was a 511.

Let alone the fact that the dial in all of these was the rotating cylinder with the surface facing the operator and so the numbers moved up-down, while in the 20 it was a circular sector type and the numbers moved left-right.

Another tell-tell sign also is the tube shield.
And, of course, the face with the knobs widely spaced in the 85 and such, vs the small triangle in the 20.