I searched, but as usual, I did not have any success.

The owner's manual states 75w85 (rear) synthetic hypoid and the front 80w90 dino. I believe an SSM was posted stating that cold climates should use 75w85 in the front.
I downloaded the Motorcraft attachment which shows the 75w85 for the front. I am changing fluids this weekend. Has Ford updated the front to 75w85 synthetic for all 2015 and later trucks?

 

I just happened to have a '20 owners manual on my desk and it specifies 75W-85 synthetic for both ends with no mention of anything for seasonal use.

 

I discovered that my local dealer's parts department is open today (Saturday). He stated that a product change was published earlier this year. It updated some earlier models to 75w85 synthetic in the front differential and Mercon LV in the transfer case. Evidently, the update replaced XL-12 for some transfer cases to Mercon LV. The attachment posted earlier was published in February 2021.

 

MerconLV replaced XL-12 in the standard ESOF trans case several years ago IIRC, it was already factory fill on even my older TOD trans case.

I just replaced the front diff fluid with synthetic, no reason for it to be dino oil, interesting how Ford seems to have determined that eventually anyway.