When driving my 1994 Ford Ranger xl it makes a horrible whistling noise that changes based on wind direction i.e. when I pass a semi the pressure wave makes it go away briefly. When I open all the windows it’s quieter but still there. It’s also independent of the blower motor whether on high or off. Nothing changes depending on what setting any of the environmentals are set to. Doesn’t change when window wipers are moved. Does not change base on rpm. It only comes on from 45-65mph and sounds like it is coming from somewhere on the top side of the dash on the passenger side.

 

Check door gaskets, open door and run hand over gaskets to see if any part is deformed don't forget the bottom of the doors

Do you have a roof rack?

What about side mirrors?
do they move, if so move them to see if it effects the noise

 

I noticed some cracks and shrinking in the front windshield seal that goes around the entire windscreen. How difficult is it to replace the rubber seal because might as well start there since it leaks water sometimes.

 

If it leaks water to inside the cab then the trough around the windshield is rusted out and needs to be repaired

The black molding just pulls out and new molding is available from places like LMC Truck, $70
The molding is just a trim piece, not a water barrier

The windshield glass sits on a ridge with sealant holding the glass and to seal it
Around this ridge is a trough where water collects and runs down to the lower area, on the outside of the cab
If trough starts to rust, usually in the lower corners of the trough, it will rust thru and water can then leak inside the cab

Best to remove the windshield to do the repair
But with the rubber trim removed you may be able to try and repair any holes with RTV or similar sealant in a tube

Its best to grind out the rusted areas and maybe bondo the holes and then repaint area to stop the rusting

 

Found the air leak. It turns out it was on the upper passenger Side of the windscreen. I had my friend drive while I pushed outward to listen for change in pitch and applied rtv from the inside. I couldn’t apply any from outside As the trim piece sims glued in place and has a lip that goes under the glass. There is no visible rust do you think I’m good or should I eventually remove windscreen and double check?

 

Wait for a rock chip and get insurance minus deductible to replace it
The seal between the glass and ridge has failed, so yes to fix it you would need to pull windshield out, clean it and the ridge, then apply new sealant on the ridge and put glass back in