9-Pin, 6973 beam power tubes are uncommon in guitar amplifiers but were commonly used in vintage jukeboxes by Wurlitzer, Seeburg and others.

Original 6973 tubes are now quite scarce.  A Russian remake is available but it's smaller and, to many ears, not as pleasing.

Among the vintage guitar amps using 6973 tubes are some 1950's - 60's amps made by Valco, many of them branded by Gretsch, Supro, Airline, Magnatone, National and Montgomery Ward.

On the right is one of the Montgomery Ward amps.

Its ID badge shows the complete model number:  62 GVC 9033A.

This model is equivalent to an Airline 62-9033.

The amp had one bad 6973 power tube and we wanted to install a pair of NOS American tubes.

It turns out, 6CZ5 tubes are quite similar to the 6973 in construction (see photo) and sound, and they aren't nearly as scarce.

We had to rewire the tube sockets slightly but afterward they accepted either tube type.

Besides the bad power tube, this Valco amp had a broken fuse holder (already replaced in this photo) and a broken shaft on the Tremolo Intensity control (right).