do i need to add something to my gear oil when i replace my diff fluid? my truck has limited slip.
what are the odds the limited slip is any good at 180k?

 

i found my answer. i read allot about the carrier races spinning. how common is that?

 

Seems to be the most common thing that I have heard about going wrong in the 70's. From what i hear, preventative measures like changing the bearings and checking carrier preload is the best way to get around that issue.
I had to get mine done a few months ago. Cost me a bit to get the housing machined and all the rest of the stuff installed at somebody elses labor.

 

kind of scary

 

Probably needs clutches. Take a look while you are in there. If there is a lot of slack between the spiders and side gears, the clutches are toast.

And yes, you need to use additive or a gear lube that already has it.

 

mines at almost 300miles and still seems to be working. I'd run the additive even in the stuff that claims it has it my lsd in the halfton chattered like crazy with royal purple that your not suppose to need the additive with.