OK, so here are my results:
PanAm Split-bell horns ranging from serial P-22,8XX to P-37,3XX....a NW-I of serial 101,5XX ...and a Chu (NW-II) of serial M157,XXX...have identical bodies.
Measurements taken at:
Neck receiver exterior diameter, neck receiver ferrule length, body tube diam's at upper stack A-hole, lower stack E-hole, tube-to-bow ferrule, bow-to-bell ferrule, diameters of Bell Bb hole, bow C and C# holes, and bell lip diameters.
Height from bottom of bow to bottom of tube/bow ferrule. Height from bottom of bow to bottom of bell ferrule. Distance between surface of body tube and surface of bell piece taken at tube/bow ferrule. All ferrule bands are the same width on all 3 horns.
13 measurements along the body of the horn... and all are identical (within less than a .5mm differential on all).
All necks fit and intone each other well. The necks of the Chu and NWI have a smaller interior mouthpiece end diameter than the PanAms (meaning their necks taper more than the PanAms).
Then the PanAms have no rolled holes, whereas the Wonders do.
Wowzers.....:dazed: