I suggest the following but I am an over achiever…..plus, fluids are way cheaper than repairs. Oil every 3,000, diffs, trans, radiator, brake every 30,000. This is a lot more affordable if you do it yourself, or find a non-dealer mechanic out there that you trust to do these things. None of it is hard, just getting rid of the old fluids is the PITA. In Texas, autoparts stores and repair shops are required by law to accept used oil and fluids from anyone provided there is no gasoline in it.Those prices are great, they are much lower than what 2 dealers out here in Arizona estimated I asked them last year (they didn't yet have pricing set up for all of these services).
I had my oil changed at my free 10k service, then I had the oil changed again at my 15k service. I paid $181.85 out of pocket for just the oil portion of the 15k service. I don't know what the rest of the service would have cost because I have the prepaid maintenance plan. I'll ask them at my next service which is coming up very soon at 20k. The extra services at 15k included lube prop shafts, smart key battery, rotate tires, plus full inspection.
For my upcoming 20k service, I'll obviously be doing an oil change and I'll be talking to them about when I should be changing fluid in the differentials, transfer case, and transmission. They checked my differential fluid at 15k and it still looked new.
I am on the service plan for "driving off-road, on dirt roads or on dusty roads" and although I don't tow, I do frequently carry heavy loads so I am conscious of those special service items as well. For the "towing a trailer, using a car-top carrier or heavy vehicle loading" the first recommended differential oil change is at 15k. For the off-road service schedule, the first recommended transfer case oil change is at 30k.
I'm looking through the service schedule and the only mention of transmission that I see is "inspect transmission fluid cooler hoses and connections and transmission for signs of leakage" at 30k and then the first "replace transmission fluid" is at 60k on the towing/heavy vehicle loading schedule (then again at 120k). I don't see any recommendation to change the transmission fluid unless you're observing the towing/heavy vehicle loading schedule!