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Rear diff question


BigAl

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Ok guys I'm going to change my rear diff fluid and I have a limited slip question. I can't seem to find out if I have limited slip or not. My axel code in the jamb is 86. Which checks out to be open diff. But it also says I have 3.73 gears. However the tag on my differential cover starts with 4 10. I've included a pic. Please someone enlighten me.
 
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alwaysFlOoReD

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I don't see a pic.
 

lil_Blue_Ford

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Although it's not overly common unless the previous owner was into modifying vehicles, it may have been an axle swap for different gears, you can check the numbers on the ring gear when you have it open to drain the oil. If the tag reads 4 10, it should be an open 4.10 gear. If it reads 4L10, then it should be limited slip. Of more concern would be the question "did they change the front axle gears to match?"


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BigAl

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sorry having trouble loading pics....i have a 2x4 so no need to worry about the front...my main concern was weather of not i needed to add a L/s addictive when changing the oil, so theres no "L" on the tag and the axel code reads 86 so i guess it should be an open diff either way
 
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tinman_72

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To be certain that a previous owner did not install a Track-Loc, jack up one wheel with the transmission in neutral. If you can spin the wheel by hand it is an open differential or it is a worn limited slip.
 

Die.Fledermaus

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Take the lazy way out. Assume that you might have a factory wet clutch pack LSD and just buy the gear oil rated for clutch type rear ends. It is penny more expensive and works in regular types also.
 

Captain Ledd

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That tag says it's open.

Die.Fledermaus's advice is actually pretty sound. It won't hurt anything and isn't that much more expensive.

Even though your axle looks pretty clean in there, I always tell people this advice:
Make sure you can get the fill plug open/loose BEFORE you drain the oil!. Too often that plug gets stuck and is rusted thoroughly in place.
 

BigAl

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Thanks all


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lil_Blue_Ford

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That tag says it's open.

Die.Fledermaus's advice is actually pretty sound. It won't hurt anything and isn't that much more expensive.

Even though your axle looks pretty clean in there, I always tell people this advice:
Make sure you can get the fill plug open/loose BEFORE you drain the oil!. Too often that plug gets stuck and is rusted thoroughly in place.


Well, I ran into the fill plug being rusted to junk, but since I had to replace the ABS/VSS in the top of the axle I just measured out the gear oil and put it in through there. Another, probably better solution would be to get a replacement diff cover with a fill plug


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Captain Ledd

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Hehe, me too. Ended up drilling a hole in the cover (I gasket goo'd a somewhat larger magnet in there), and then gasket goo'd a square of aluminum flashing over the hole.

It wasn't pretty, seeped just a little, but held up for the most part. Thankfully that was on the old axle, the 8.8 I splurged for a better cover.
 

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