There's this one: https://hobbyking.com/en_us/orangerx...___store=en_us

As I understand, it's basically a normal OrangeRx 6 channel receiver without the connectors for normal servo leads. You have to solder the connections on yourself.

Lemon Rx used to make one too I think, but that was DSM2 and they've now discontinued it (possibly they'll bring out a DSMX version at some point?).