Possible diff/tranny issues - 85 Rx-7

[G-Man]

My 1985 IT-A Rx-7 has the 4.77 Limited Slip from the front of a Kia Sportage. Ran the car this weekend and it seems to have started "howling" - sorry I don't have a better way to describe it.

Diff had Mobil1 75-90 LS GL-5 gear oil in it with less than five hours running time. Drained the diff fluid today. It is very dark gray - like way old coffee (with cream). The magnetic drain plug had an aspirin-size amount of goo on it and there seem to be some teeny silvery pieces in suspension. I drained it into an empty clear soda bottle to see what settles out.

Here's another video that may help with diagnosis -
Direct link - "http://www.youtube.com/watch?v=hO2t7Ko5d_I"
[ame]http://www.youtube.com/watch?v=hO2t7Ko5d_I[/ame]

Attentive readers may recall my earlier post with possible rear axle issues. I'm not sure if this is related -
https://improvedtouring.com...ad.php?t=28967

Any ideas? Thank you for the help!