I dont think it is the drive shaft it sounds like comen from one of the dual pipes but not sure. you can hold the brake give it gas and it makes it, and you can here it just by reven the engine up to.

Yes you can drive it in four wheel drive mode.

some bolts are tightened using a thread locking compound to make sure they wont loosen , do they look badly rusted< us a spray lube ,make sure you have the exact socket and it fits tightly, if its a hex bolt a six point or a 12 point or a torx head an make sure you have good tools that wont brake easy, and that you have leverage , if near gas tank heat or flames are not suggested good luck hope it helps you .Woody

You may have a dirty throttle body and intake manifold

I think you may have a Cat. Converter plugging up. It can make the car run bad and give an unholy vibration. You could remove a front O2 sensor to check and see if it runs better with it out. I have seen this before on an Escape. Also have had bad coils. Ford has had some trouble with them. The ABS is most likely a wheel speed sensor. They read off a ring on the CV shafts. You should inspect them for missing teeth. Other than that if you have access to a scan tool, drive it while watching the datastream and look for a wheel speed sensor dropping off to 0 or 3 mph when braking. Hope this helps.

check the barings in the rear end and on the axles see if the fluid is all over the brakes

This sounds like the front drive shaft that may have worn u joints. Put the vehicle in park, set the brake and proceed to shake the front drive shaft up and down to inspect for wear. Let me know what you find.

Sounds like a bad U-Joint.

On this particular truck this is bad news.. unless someone has already replaced the factory ones once.. as the factory ones are pressed in you may need a special tool to get the old ones out.

A driveline shop may be able to do this for you.. and check with the Ford dealer for their repair procedure.. many folks have simply had to replace the entire drive shaft with new U joints.

They will be aware of the issue.. have them check service bulletins etc.

You can have someone check the location of the noise by keeping your foot on the brake.. placing the truck in gear.. and giveing it a little gas.. putting strain on the drive train.. shifting back and forth.. rolling a foot or so.. repeat.

The other things to check.. Motor mounts.. and transmission mounts..

Motor mount.. simply observe the engine with hood open.. and rev it up a little.

Best of luck!

There are many things to try. Check your balljoints, shock towers and springs. Recheck how you hung the brake calipers. The hoses can go two ways, only 1 is correct.

If no luck look at motor mounts and check fan shroud for blade clearance. Check pulleys. Then move rearward to heat shields, exhaust pipe and gas tank. Then look at the frame.

Look for scrapes and shiny spots underneath the car and check the driveshaft for bad joints. Thats about all I have for you.

this fluid is likely to be diff oil its the axle oil seal needing replacment and you could do this job yourself take off the prop shaft and the drive flounge to reach the seal fit a new one but oil it and put the drive floung back on dont over do the nut,,,as for the u joints,,, grad hold of the joints with both hands and twist them together if the dont move or twist there ok,,,,a 4.7ltr engine is thursty but at 86k its just about run in with 1000s, of miles to go yet if its broping on mpg try giving it a realy good service and dont drive it so hard????

In all probability the drive shaft universal joints are running dry or need replacement. Try greasing these before you have them changed.