I had this problem, the weather stripping had come loose. Try removing the water deflector (underneath the wipers). If the weather stripping is loose, put it back into place with some black epoxy.
My guess would be the cowl drains are plugged up with debris. Remove the wiper arm assemblies and the cowl panels/screens and clean out the drains.
the starter on all Pontiac 326-455 engines are on the drivers side of the engine.
Bottom front drivers size
Under the Dashboard on the Drivers Side.
its on a sticker on you drivers door.
Look on the drivers door for that info.
under the hood on the drivers side.
i need parts diagram for2000 Pontiac Montana drivers side door
beside the drivers seat...on the floor
On the drivers side firewall
On the core support, drivers side of the radiator.
underneath the drivers door