The nice UPS man delivered my AMSOIL 75W-110 today, so I'm planning to do both differentials tomorrow. I've gotten conflicting answers as to what the proper fill level is. Some sources say fill till it comes out the hole, others say anywhere from 1/4" to 5/8" below the hole.

What's the proper fill level for a Dana 80 rear and 60 front?

Right up till she starts coming out the hole.

yup. . .

the 1/4 below the hole is for us 3rd gen guys running the AAM axels.

if you have a LSD make sure to toss in some friction modifyer to keep the clutch pack happy.

when it starts to dribble out, thats when ya cap it off!!







make sure to have the axle leveled horizontaly. the vehicle may be inclined one way or another, but you want your axles to be level to the ground. otheriwse you may underfill the diff.

So what happens if my fluid level is higher than 1/4 from the top? I have the 3rd gen and my fluid started to dribble out of the hole when I stopped filing it??

The manual for my 04.5 says to fill the 11.5 AAM to "1/4" below the fill plug + or - 1/4"
Well, that means that anywhere from 1/2" below the hole to right at the hole is acceptable. I would just fillingit until it comes out of the hole, because if a little is good--more is better
Remember to make sure is parked on a level surface when you do it

I don't know why they try make it so complicated

Why didn't they just make the hole a 1/4" lower....

Thanks gents... all went well. Only had time to do the rear, but the front is coming next.

As a side note, this truck has been in the family since new, and after talking with the previous two principal drivers (father-in-law and brother-in-law), I was a tad concerned that the diff fluid had possibly never been changed... 240k miles! But when I got in there it was obvious someone had indeed changed it at least once, unless the factory is extremely messy with red RTV. The fluid was in pretty sad shape, with some sludge at the bottom, but after a good clean-up all looked fine. (Man, that crap stinks!)

Anyone know what the torque spec is for the fill plug? The (relatively worthless) Haynes manual says something to the effect of "tighten it securely." I applied the same 35 lbs the diff cover bolts called for and called it a night. Am I OK, or is more oomph needed?

And is it necessary/recommended to add the friction modifier to the front diff as well? I'm assuming not...

35ft lbs seems like a good number for the plug.

Drew on the third gens it says that theLSD diffs don't require the extra additive is this correct? or what would you recommend I just did my diffs a few months ago, but don't want to "f" them up.