Conn gets its own page as the underslung, folded-back tuning slide was used on many models, and these examples are common enough to be had easily.
Type: Cornet
Brand: Conn
Maker: Yamaha
Model: Director
Model â„–: 19A [21A has copper bell; not shown]
Where made: Japan
Dates of manufacture: ~1971 [1973 - 1977 for similar 16A]
Below is the 1972 Conn brasswind catalog entry for the Conn 19A Director, designed by Renold Schilke, and manufactured by Yamaha. This model was only made in 1971, available up to ~1973, and was discontinued in favor of the American-made 16A by 1973. In 1977, the design of the 16A changed from this underslung tuning-slide model to a more conventional layout.
Here is the full catalog page:
Notice that the 76A Connquest cornet [with tunable bell] is present.