1981 E38 Port Aft Cowling Vent

My 1981 E38 has the port side aft cowling vent and under deck dorade box. The vent is sealed off with the screw plate. I'm looking to find a cowling that will screw into this vent as it seems to be an odd size and thread. Sometimes extra ventilation into the quarter berth would be nice hence me looking to get the cowling option.

Any suggestions? or pictures if you have a cowling vent in that location.

On my boat, this cowl also fits that port deck vent plate.