Will have to check out that Allan Chase disc.
John McNeil "East Coast Cool" and Joe Morris' Bass Quartet are two other pianoless quartet discs he appears on.
Though two basses make it a quintet, Charles Tyler's Nessa date is also excellent (and finally back in print).
Some piano-less quartet music also makes it onto the Braxton Arista Mosaic.
Frank Lowe had a great band with Earl Cross, Didier Levallet and George Brown that recorded for Palm and Marge - some of this material is available on CD. Also the early David Murray stuff with Olu Dara is very, very nice.
Though Osborne's heaviest work was in a trio, this quartet is pretty nice stuff. Also, here's a fine archival date from Bobby Bradford (w/ James Newton; you'll have to scroll down).
Some out of print gems that hopefully make their way back into regular circulation:
Ric Colbeck - The Sun Is Coming Up - (Fontana)
New York Art Quartet - Mohawk - (Fontana)
Steve Lacy - Sortie - (GTA)
Ted Curson - Tears for Dolphy - (Fontana, w/ Bill Barron)
Ted Curson - Urge - (Fontana, w/ Booker Ervin)
Alan Shorter - Orgasm - (Verve)
Bill Dixon/Archie Shepp - Quartet - (Savoy)