trac lock 3rd member

is this a trac lock 3rd member or some other ford posi .i need to know because i want to buy new spider gears for it. it is 31 spline and i need 28 spline.
thanks john
P.S. bryant can you help me out on this

 

How about answer 'C' its not a posi unit at all, standard open rear end

Look at your axles where the tire bolts too, if the center part of it has 3 drilled holes in a row its the 31 spline axles. Here is a photo of what a 31 spline axle looks like. By the way this method only works for axles made up to 1972. After that date all axles switched to concave centers.

 

I think it is Ford's Trac-loc. If you look at the back side of the differential where the ring gear bolt heads are you can see the recessed area.
On an open unit that area is flat. At least on the ones I have seen.
Yours should have clutches in it. The side gears are what needs replacing to change the splines but I am not sure if that is all it needs or if that will work for sure.
clint

I could be wrong though as I am used to working with 9" units

 

Looks like a Trac-Lok, look for a part number on the differential.

 

Make sure you know which version of the positive traction you have before you buy a rebuild kit. Compare pictures/part numbers. I've seen to stock versions out of 9''s and they weren't the same. Close, but not the same so becareful before you waste some money.

 

yep thats why im asking for alot of opinions all the pics and articles say it is a trac loc 3rd member so next to find out what version. hopefuly bryant at san diago gear and axle will come thru for me if not he should be able to tell me what version i have.ialso know someone in kentucky that rebuilds them i am trying to get a hold of him now.he goes to alot of swapmeets and sells complete pigs and just gears. so before this is all over i should end up with a good rebuilt 3rd member.

 

I think there are 2 ford units. There were some older units that came with Detroit lockers in them but I am pretty sure that was only in trucks.
The Trac-Loc which is the most seen and the older Equa-Loc ( Spelling?) which is the older one. There again this is based on what I have seen in 9" units so it might not be the same. I think the clutches are the biggest change.
Take it apart taking a lot of pictures and look at the clutches. Then compare then to what pictures you can find on them. That will tell you what it is.
I can look in some of my Ford books and see if I can find anything for you. IF I can figure out my new scanner.
clint

 

Ford put the Detroit Lockers in high performance cars starting in late 1969.

That looks like a 9 inch Trac lock, like has been mentioned.
My guess is it is from a 4x4 truck or Bronco. Still pretty common to find in junk yards. 31 splined axles make them a slight hard sell.
I used one of them in my 1968 Cougar 5 speed conversion.

The truck units will have the larger pinion yoke.

I am not really versed in these Ford posi units, I have heard of 2 and 4 pin trac locks.
Pretty sure that a Detroit locker will have a machined look, rather than a cast look found on the Trac locks.

 

A Detroit would replace the entire Differential right?
I can't tell by looking at the back side if it is an 8 or 9".
The 76 F150 4x4 I had was a 9" with Trac-Loc in the 9" rear and whatever Dana put in the front. Pretty sure the 9" was 31 spline. Then you have the different bearing sizes to deal with. I have seen at least 3 bearing sizes on the 9" axles plus at least 3 different yokes.
Ford never said it would be easy. lol
clint

 

what did that come out of ?? I am assuming that you know that if it is a 31 spline then it is a 9 inch and not an 8 inch, because 8 inch rears only came in 28 spline stock.

 

not sure what it came out of but it is a 31 spline and yes it is 9 inch that much i do know and from what i am finding out it is a trac loc posi.so now i need to find some 28 spline spider gears and to also figure out if it is 2 or 4 pin.might just end up taking it to a pro and have it rebuilt while im at it. if worst comes to worst i can just put the 411 gears in the war pig that was in the rearend that came out of the car.

 

Now I might be totally wrong on this but... If you look into the side where the axle is supposed to go and see a cross then it is a 4 pin spider gear. You will see one pin that goes across and a short pin on either side of it making a cross. Been a while since I have looked at one that did not have the Richmond Lock-Rite in it.
clint

 

Here is a good source of information
http://www.kevinstang.com/Ninecase.htm

Rotate the gear about 45 degrees and post another picture of it like in the first photo. We should then be able to see if it is a 4 pinion.

The WAR housing is actually weaker than the C7AW housing it is currently in.

 

yes that kevinstang site has a wealth of info ive been reading it for a couple of days now and also bryant at san diego gear and axle has been a big help he is looking for a set of spider gears 28 spline for me.
thanks clint i will try to look for the pins to see what i have will also take more pics after supper.

 

just took more pics and it looks like there is one pin going all the way across and two shorter ones making a cross