Are you sure you are looking for a 3/4" corrugated hose fitting? AFAIK that is only on the Mares BCDs. Oceanic and Aqualung are 1/2 inch, and Scubapro, Dive Rite, OMS, etc etc are all 1" corrugated hoses.
If you are sure that it is a 3/4" corrugated hose, then you can get a Mares which either fits a 3/4" hose or adapts to it. (Check with a Mares dealer to be sure which). Or you can get a Atomic SS1 which has adapters to fit any corrugated hose I have ever seen. I am a big fan of the Atomic SS1 because it has several design features which will make it more reliable and longer lasting in actual service (made of stainless not chromed brass, integrated cap, seat saving orifice), but Atomic does not have the dealer coverage that other brands have.
As far as I know those are the only choices for a 3/4" corrugated hose.