FORD 9 INCH TRAC LOCK
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Joined: Mar 2002
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FORD 9 INCH TRAC LOCK
OK I EMBARRASSED TO SAY I HAVE NO IDEA HOW TO TELL IF IT IS OPEN REAR OR POSI UNIT WITHOUT CRACKING OPEN. I HAVE ONLY WORKED WITH GM UNITS WHICH THEER IS A PRETTY OBVIOUS DIFFERENCE. I HAVE TO LOOK AT USED UNIT AND DON'T WANT TO LOOK STUPID. IT APPEARS IN ANY DIAGRAM THAT I HAVE SEEN THAT IT IS CLOSED WITH NO INSPECTION TYPE HOLES?? PLEASE HELP AS I DON'T WANT TO WIND UP WITH JUNK? LARGE OR SMALL JOURNAL??THANKS
Laughing Gas
Joined: Mar 2002
Posts: 948
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From: Newton Illinois
FORD 9 INCH TRAC LOCK
[updated:LAST EDITED ON 21-Mar-02 AT 10:52 PM (EST)]jack up rear end put in neutral rotate tire on one side.If tire on other side rotates same way it is a posi.If tire on other side rotates backward it is a open dif or non fuctional posi.Hope this helps.If you want more info on 9 inch there is a forum for transmissions and diffs.
Larry
Larry
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Joined: Sep 1999
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From: Pensacola Florida
FORD 9 INCH TRAC LOCK
It has been awhile but I believe you can look for the tangs on the steels. On the carrier there will be machined spots for the tangs to index. Some have 4, some have 5. I think that this is a realiable method. You can also tell if it is a two or four pinion rear. Don't take this as fact but I think I'm right 
Charles in Pensacola
Charles in Pensacola
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Joined: Jan 2001
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From: Virginia
FORD 9 INCH TRAC LOCK
Boy, I am confused.
1. The previous poster's method of jacking up the rear and turning the tires IS and accurate way to test the factory unit. It could fail the test and still be a LOC, but it will be wore out like he said.
2. If the 3rd member is out, it's obvious if it's a LOC. The spider gear has a flat area on the back of it and you will see a bunch of discs behind it.
1. The previous poster's method of jacking up the rear and turning the tires IS and accurate way to test the factory unit. It could fail the test and still be a LOC, but it will be wore out like he said.
2. If the 3rd member is out, it's obvious if it's a LOC. The spider gear has a flat area on the back of it and you will see a bunch of discs behind it.
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