Posted by matchmaker on February 22, 2004 at 14:11:36:
This might (??) be a .750" bore York sousa - with 3 .750" bore pistons and plenty of .750" bore slide tubing.
You (again whoever bought that ebay detachable bell BBb 6/4 3-valve front-action Holton from Wichita Band Instrument Company) might be able to pick this up cheap and have some stuff to use to make yourself a 4th valve and slides...??