usual places. behind door cards, underneath scuttle, sunroof channels, heater motor on mk2's
not so usual places. rubber grommits between boot and roof. window seals, if you find its leaking through a seal then its best to get the window removed & re-fitted as you'll find its rusting away also below the seal!!
jv - Rallye windscreens are bonded are they not. so it shouldnt be leakin in there. unless its had a new screen in its time