2016 RAM CTD; Can’t Find Differential Service Interval!

I'm in an 6.4L truck, but this is what my gear oil looked like when I changed it at 24k. A little bit less than half of those miles were towing and mostly with our trailer that's around 9k. I expected dark oil for the first change, but this stuff was like midnight and looking very no bueno. If anyone has the factory stuff in there, then I would err on the side of caution and get it out of there sooner than later.