[Ron Ramirez]

The gold decal on the back of the upper chassis, underneath "PHILCO RADIO" does it read "Model 51 Superheterodyne" or some other number?

That 51 chassis would have to have an oversize power transformer to handle the extra load of two extra tubes in the shortwave converter chassis. Unlike the standalone SW converters Philco sold, these only have two tubes and get their filament and B voltages from the main chassis. The standalone Model 4 has three tubes, including an 80 rectifier and its own power supply.

I see what you mean, your set does not have the routing in the wood at the top as does the 470/490.

I believe this was most likely put together at the factory, using leftover chassis and cabinets. Just like later on, when Philco built a few 52 chassis into their grandfather clock cabinets, as just one example of another factory issued Phranken-Philco.

I sincerely appreciate your sharing this with us. This is a previously unknown variant of the 470/490, and it's always great to be able to document these as much as we can.