Can you guys tell me whether its locking or limited slip. It doesnt have an axle tag. Its on a '67 F350. Also, do i need limited slip supplement or something similar if it is locking?

 

To test, lock one wheel and using a breaker bar try to turn the other wheel. If it snaps while rotating, then it's a locker. If it just slips, then it's a LS.
The break away torque for a LS should only be like 60 ft/lbs depending on how worn it is.

A locker needs no special friction modifier.

 

AXLE code stamped on the 2nd line-far right of the Warranty Plate, riveted to the left door face below the latch.

If the code begins with a letter: Limited Slip // If with a number: No Limited Slip.

Ford confusion: Referred to Limited Slip as locking, but this isn't the ratchet type Detroit lockers used on cars for drag racing, etc.

These have steel and lined plates (see pic). Some 1961/62 F350's, 1963/84 F350's have Dana 70's.

 

You can use this to identify a Dana axle Bill Of Material (BOM) number located on the axle tube, and to identify the type of carrier used:
https://therangerstation.com/tech_li...ana_axle.shtml
https://therangerstation.com/tech_li..._1967-1978.pdf

 

At first glance I thought you had a Dana Power-Lock (or however they spelled it) which is a very desirable limited-slip differential.
But it looks just enough like one of the old No-Spin / Detroit Lockers for a GM 14-bolt that I'm reserving judgement until someone with more knowledge chimes in.

I was not aware that Ford offered the Dana unit, but they did use several as the optional limited-slips over the years.
And as said, if it came from the factory it was a "limited-slip" and not a true locker. At least as far as I know.

Paul

 

Checking by the method I mentioned above would confirm clutch or locker.

 

Hey Freight, when you say 'snaps' you are meaning makes a snapping noise??

 

That looks like the same 2 piece open carrier I have in a 70 and not the Powr Lok. The Powr Lok has an more solid button case side and an longer opening in the flange half of the case around the cross shaft to allow it slide to lock the axle half's together. You can install a No Spin (Detroit Locker) in that diff.

cstoyer

 

I've been told that this Dana 60 Rear End from a 1971 High Boy 4X4 is a posi traction. So would that mean Powr-Lok or Trac-Lok? Is there enough in this photo to tell which one it is?

Is posi traction the same as limited slip? Or what's the difference?

(Edit: This photo is the front differential, posted initially by mistake.)



(Edit: This is the correct rear end photo.)

 

Good question. Someone will know for sure, but I think Dana had a couple of them over the years. Just not sure where one was used over another.
And after all these years I still have a hard time remembering which ones were Ford 9" specific (Traction Lock maybe?) and which ones were Dana specific.
Embarrassing since I've had all the books and sold the different models over the years. Heck, with all the variations on "traction" and "lock" in use, I still can't remember how each one is spelled!

That's just the part number for the ring gear, plus some extra info used in production. Gives info on the ratio and the measured clearance for the builder to get an initial starting point for setup.

Yes. Limited-Slip is the "type" of traction differential. A "Posi-Traction" is a General Motors specific limited-slip diff for their GM corporate axles only. In other words you can't buy a Posi-Traction (or "posi") for a Dana or Ford axle.
Unfortunately like some other things, Posi-Traction has become a generic name over the years. Good marketing by GM apparently, passed down from generation to generation. But Posi is GM only.

Whether using clutches, gears, or some other method of transferring torque to the spinning axle, a limited-slip is any differential that is not a full locker where there is a mechanical connection between the two axle shafts.
So "open" has nothing connecting the two sides, "limited-slip" has some method of driving both, and "locking" has splines or teeth or some method of locking the two sides together under some conditions.
Sorry if you already knew that last part, but figured I'd add it in there anyway just in case.

Paul

 

You need to read my post above to ID Dana axles.

 

Thank you. This is helpful, very. As I learn about these terms, I could see they are used loosely. So with this rear end from a 1971 Ford F250 4X4 it would be called "limited slip". But means the same thing as "posi". Now I just need to get some more details to figure out if it is Powr-Lok or Trac-Lok since can't tell just from the ring gear part number.

My next research will be to try and figure out what brakes these are. The info I have so far is that they are from a Chevy/GM 1977 4X4, but I haven't nailed that down.

 

If you find the BOM (bill of materials) number stamped into the axle tube of the Dana axle and put it into the database in Rich's post, does it give you the type of diff specifically? Or does it just state "limited-slip" and leave it at that?
It might leave it up to us to know what would have been used based on the year or application, but you never know until you try.

Those BOM's are pesky things sometimes though. Very shallow stamping in the long-side tube facing directly to the front. Sometimes so shallow that dirt obscures them completely, and if you use too aggressive of a technique to clear them up, you can grind off the numbers themselves!
But if you find them, try inputting them into Dana search database to see what you get.

Regarding the brakes, they look to be the typical seventies-to-eighties GM front calipers. Based on the lack of a parking brake is how I'm concluding they're fronts, but that does not guarantee anything. Just makes it a better bet.
Same caliper style used from about '73 to '80-whenever (or maybe even later?) GM K5, K10 and K20 trucks.
There was a subtle change in '76 however (same time they went to GM corporate brand axles vs the Dana models) and the ones we use for the Bronco front conversions were the early '73 to '76 style. Not sure what the differences are, but they look very similar.

Paul

 

Dana lists either a Power-Lok, Trac-Lok, or a No Spin available in a 4.10 ratio in the catalog. You have to find the right BOM for it. Dana doesn't have this info online anymore so you have to use this catalog.

 

I don’t think that is any kind of limited slip, based on the top picture. You can see the spider gears of the open diff. If it was limited slip we would see some kind of clutch pack... A better shot of the diff with the cover off would confirm