This brass instrument specialist recently made replicas of brass
trombones for "either a Wurlitzer band organ or a similar German organ":

    Robb Stewart
    140 E. Santa Clara St., #18
    Arcadia, CA 91006
    tel/fax: 818-447-1904

Stewart is a renowned craftsman and has made many playable replicas of
"extinct" brass instruments for Civil War bands, etc.  He showed me an
original organ trombone, missing the reed exciter, which played a bass
D-sharp note.  The length is 78 inches.  The bore at the exciter is
about 5/8-inch, and just before the bell it's about 2 inches.  The bell
is 8.5-inch diameter.

Hanging from the ceiling Stewart has a collection of old trumpet bells,
"in case anybody needs some."  It looked like there might be 20 bells,
just enough for a trumpet rank in a band organ!

Robbie Rhodes