Squealing noise coming from behind transmission pan?

[nobb]

At high speeds (80+ kph), a squealing sound is audible in the front from our Ford Freestar minivan intermittently. It's a FWD by the way.

I jacked up the two front wheel and put the van in neutral. Spinning driver's side front wheel, there are no problems. Spinning the passenger side front wheel, there is a squealing noise. It's definitely not the bearings, because the source of the noise seems to be from behind the transmission pan area (differential?).

Strangely, if I were to rotate the passenger side front wheel clockwise (as if the van was going forward) then I get a squeal, but if I rotate the wheel counter-clockwise (as if the van was going in reverse) then all I hear is transmission fluid sloshing around but no noise.

Im completely stumped now...anyone have any ideas what this could be and how to diagnose?

[mr2mike]

leave the wheels jacked up. Be careful while attempting this, have someone ready to brake the van.

Take a long screwdriver and press it against the axle nut by the wheel and listen on the other end. It could still be the wheel bearing. Noise can transfer all over the place.

Could also be a CV joint on it's way out. Check the boots. Any cracked or grease leaked out?

[nobb]

Wait, what's the point of the screw driver on the axle nut thing? What are you looking/listening for in that?

Dont think it's the CV joint...the noise is definitely coming from the transmission pan directly because while rotating the wheel I have my head right up underneath it. No signs of wear on the rubber boots.

[mr2mike]

The screwdriver just helps find the actual source of the sound. But if you're certain its in the pan, then I would buy a transmission filter with the intention of changing it.
Drop the pan. See what's going on. Clean it up and change the filter. Maybe some synthetic tranny fluid can quiet it up and help it last longer.

Sorry, I've got nothing. Maybe try a dedicated Ford Forum and see if its a common problem.