I'd try a local racing shop that supplies parts to race cars. If they don't have it, I'd try a local industrial shop that sells these type of supplies for industry applications. You might also try www.gen-aircraft-hardware.com. They have a good catalogue. Hope this helps.
reeve airmotive has a nice small one.... (907)272-8522.....
they give me a new one whenever i come in there using my hands going "you know, one of those fittings with a du-hicky and a whirly-gig on the other end"