F-150 Front end grinding

You must have a manual transmission. Rebuild it. synchronizers are bad. The reason for grinding. Then you have worn shift forks. Reason for popping out of gear. Also replace any worn bearings or just get the bearing kit and replace them all, with the races.

make sure that your vehicle has a "on the go" 4wd operation
if not , you will have to all but stopped to get around the gear slashing
if you have "on the go " engagement , then is a problem in the synchro rings of the transfer case
take it to an accredited transmission specialist for a proper diagnosis

Could either be a bad vacuum line or the TSB for the IWE solenoid.

If you have the truck running in park ( parking brake, chock wheels, necessary safety precautions ) check the vacuum on the front right IWE vacuum line. there are 2 vacuum hoses on there, 1 is the vac, the other is the vent, which routes up into the engine compartment, and is not hooked to anything.

Usually if it is the TSB, both sides will be making the grinding noise, as they are a common IWE solenoid

TSB : http://my.voyager.net/~sscully/file_tsb06_08_15.pdf

Operationally vacuum holds the IWE ( Integrated Wheel Ends ) out, and once vacuum is removed the spring engages the IWE.

Block diagram of the IWE vacuum system

1st, pull the vacuum lines on the IWE ( Integrated Wheel Ends ) down on both front wheels. There are 2 hoses, 1 is the vacuum line to keep the IWE spring pulled out so the front axle is not engaged, the other is the vent line into the engine compartment ( not connected to any thing ).

The issue you have sounds a great deal like the TSB published for the IWE solenoid, where water can get into the vacuum system, and not completely disengage the IWE gear ( causing it to be part engaged, and ratcheting the teeth of the gears, wearing them down ).

The truck will feel like the parking bake is on, while the vacuum line is pulled ( you are pushing a dead axle ).

The vacuum line and IWE solenoid are easy to test with a vacuum gauge, to find out if it is the line, the IWE solenoid or the vacuum supply to the IWE solenoid.

The TSB in PDF format (right click save as : )
http://my.voyager.net/~sscully/file_tsb06_08_15.pdf

Here is a block diagram of the IWE vacuum system


Operationally vacuum holds the IWE ( Integrated Wheel Ends ) out, and once vacuum is removed the spring engages the IWE.

Sounds like your axle seals have leaked out all the fluid. Take it to a garage and get a free estimate on it and they will check your axle seals.

I have a Ford F150 1989 When i start it, it makes a horrible grinding sound

I agree with duane_wong on this one ( not like he was looking for my approval :) ), it sounds like a problem with the IWE ( Integrated Wheel End ) on that side.
Quick test, when you are in 4H ( or 4L ) does the noise still happen ?
I would say cracked vacuum line to the IWE, or a problem with the vacuum diaphragm in the IWE. You can test by having the motor running in park, and in 2H, and check the vacuum line at the IWE for vacuum. Make sure you test to the vacuum line, not the vent line ( ends in the engine compartment, not hooked to anything )

This is a block diagram of the IWE vacuum system

This sounds like a wheel bering. If you turn left on a bad passengerside bering it growls louder because more pressure is shifted onto it.

CHECK YOUR UNIVERSAILS COULD BE WORN OR DRY U NEED TO PULL OUT THE SHAFT TO CHECK PROPLEY CHECK FOR STIFFNESS AND NOTCHEY MOVEMENT

Its most likely either or, if its a high pitched sound its probably the wheel bearing. If its a growling/grinding/clunking sound its probably the CV Joint. However, your problem more than likely lies in either/both.