I have a 2000 25 outlaw ,got it mid summer last year, in motor compartment there is a garden hose fitting with check valve , need info on how it works & who made it back then, no #s or names on it

Is it inline with the hose that goes from the sea water pump to the transom assembly? It's probably to be used for flushing the motor when the boat is in the water, or without muffs. Connect a hose to it and close the valve to flush the motor.

its hard to see the route of hose, when i winterized it ,I pushed antifreeze into it with pump, came out drive unit , most have done everything rite ,she made it

Most of the time they're so you can flush the saltwater out with fresh water.

Ok so if you connect a hose and have the valve open water will come out the drive. If you close the valve you shouldn't see any water come out the drive. Makes flushing easier than messing with muffs.