As you can see the fluid does not look very good, I climbed underneith this morning to add diff fluid (it was only slightly low) and then I saw this, back in 2017 when we had the hurricane the interior was soaked the engine filled with water, so did the differential, I had the fluid replaced and never though about again, I now think maybe I should've had it done a few times (I had to have the engine oil changed either 2 or 3 times before it looked normal again) so I'm assuming that's why it looks like this