On 3rd alternator ,cant get them to charge the battery and in turn they keep burning out

wow test the alternator next, 11 to 15vdc less is bad ALT(AT BAT TERMINALS LUGS)
find a shop that can do electrics.
keep and open mind.
say will not crank , not will not start or answers WILL BE WRONG
so it started and they did not once check all fuses and the alternator
if they replaced the ALT and did not remove the NEG lug from the battery then the blow up the 100amp huge alt fuse
making alt dead forever.
or the other 3 alt fuses blown.
find a real shop with real ASE techs,

also learn that ALT can short one of its huge internal 3 phase DIODE
and now the ALT I HUGE NASTY NOISE GENERATOR AND LAMPS FLICKER AND ALL COMPUTER IN THE CAR GO STARK MAD.
WE SCOPE THE ALT TO SEE THAT HUGE NOISE ON THE BATTERY.

BAD ALT i BET.
THE WORST FOR HE WORST.
OR BAD GROUNDS TO ALL THAT.

so you replaced it with wrong alt. how fun that.?
but what is wrong I bet is thjis
not doing step1.
S1: remove battery neg lug first.
s1a if not dont the you blew up the huge alternator main fuse
connected to the huge alternator stud wire. boom its blow up
and 100000 new alternators fail and there are more fuses too.
check them all ,skip none, that means too FUSEABLE LINKS
and do not let clerks tell you what to do. they are NOT TECHS.
find out what the truck needs first
even here is clear

sadly the SM tells this,. yup used 4 types of ALT here.

1. Rear Terminal, External Regulator, External Fan Alternator
2. Side Terminal, Internal Regulator, External Fan Alternator
3. Leece-Neville 165 Ampere Alternator
4. Integral Rear Mount Regulator, Internal Fan Alternator

lost the old OEM working (before) alternator I hope not. did you?
this is one schem./

Link "J) blow if battery lug not pulled first NEG lug.
has internal regulator here. no ECU override on 5.0


hard to find truth here, the books do not cover all 4 ways.
some ALTs are born dead with charge lamp burned out.
so make sure it is not. (called self excitation path)

Andrew is not 100% correct. You should be able to run the vehicle without the battery. It is there to start the vehicle or provide power while the motor is not running. You tested correctly. Check the cable from the alternator- sometimes there is a fusible link in the cable. This could have burned.

Check the fuses in the engine compartment

may hav burn a shift solenoid--put car on a scanner--local parts place does it for free--nomerical codes will show and explained in a manual--but bfore replacin a part a more detailed scan shud b performed

Battery wont make an engine die only bad alternator or missing belt. check both belt and alt output.

First thing is to ck the charging rate of the alt. It should be between 13.6 and 14.2v. Checked at the battery terminals. The lower the voltage the higher the amps. So, On a low batt, you would want around 13.6v and a fully charged battery around 14.2v.. Test alt with engine running, note charge voltage with everything off. Turn headlights on and charge voltage should drop as low as 13 volts. If volt reading is at or above 14.2v, the alt is putting out minimum if battery is full harged. Proper battery connections are very importantand battery to engine connrctions, especially the ground bolted to the engine should be double ck'd.
Here is something to note!
Fords use fusible links in the charging and other electrical circuits. A fusible link is a lentgth of real small wire that burns in two if the wire is overloaded or shorted.. They look like cylinder made of rubber on a wire. To ck, pull easily on both wires going into and coming out of the rubber cylinder. If it stretches, the fusible like is burned in two. More than likely it will be in the group of wires running across the top of the radiator.. If it needs replaceing, fusible link wire is available at the parts store. Good Luck Ned

How long did the 2nd alt. last before it died? The voltage regulator is, I believe, attached to the alternator. Have u had the voltage regulator checked?

I have had a string of bad alternators through my shop lately all made by USA alternator. I would breakdown and get an OEM part in this case. I would also bench test alternator prior to installation

Yes, but 1st verify the alternator is at fault, if you have done this then with a few hand tools you can "do it yourself" Make sure the battery has a full charge before you restart the car with new alt. or you will overheat and burn out the new alternator.