Leonard I'm afraid there's no quick fix when it comes to leaks,unless it's really obvious!
It's a process of elimination, start high up with a garden hose,some help there would be good,while you're 'pulling shapes' under the dashboard,and work your way round the windshield,then onto the cowl section,in fact anywhere you think you could get water ingress.
Dusting body seams with talcum powder can highlight leaks too,plus depending on what talc you use makes the cab smell nice too!
Good luck on your search.
Jock.

Last edited by jockbolter50; 01/10/2011 8:20 AM.

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.