Looks like it's good you changed it. Pretty mucky in there. I bet I have some pits in my 66 rear as well. If you think about it, half the gear sets in 80/90 and the top half doesn't. You might get some rust and pitting on the top side after setting 10 uears or so. I have a little noise from back there. It doesn't change pitch when I go around corners so it's probably not axle bearings.Ok so an oil change for the dart also turned into a diff fluid change. It took me pretty much all day which I know it shouldn’t have but I did it. Overall the gears aren’t bad. Eventually I will need to change them since they have some pitting on them but it will hold for now. View attachment 1716273172