I have water getting into my 1981 first gen brat when it rains.  I don't have to drive it, it comes in when it is just sitting. Seems to be only on the drivers side.  Can't seem to find where it is coming from.  I am up for ideas.....

Probably your window seal. Is it pudling up on the driver side floorboard? My first gen was leaking from the plastic window seal insert right above the steering wheel.

Either that or from under the cowl.

 

See that cowl in front of your windshield ?

Take it off and clean out any debris down in there. Then determine if you have any pinholes thru the rusty areas.

PRP has new windshield gaskets. And I have one new one left too. Ours ( the USMB Group ) were made the same time their batch was.