It's easy to be confused. All the "other" Jeeps use ATF in the transfer cases since they're chain driven, and now that CJs are becoming less and less common, I think people just assume they're the same as a YJ. (How many times have you had your Scramblers called a "Wrangler" lately? I've had it happen twice in the last year.) (I'm also excluding the BW1339 which used special fluid.) I did learn that AMC made a special fluid for the Dana 300 as well as the T-5 in the '80s, and even have a couple quarts still tucked away somewhere, but the reality is that 80W-90 works just fine for the Dana 300.
Similarly, our version of the T-5 also uses gear oil. That's different than the World Class T-5 used in Mustangs and Camaros, which use ATF. And the AX-15 also uses ATF.
(To make things even more confusing, after upgrading my wife's NP231 with the 1.25" chain and 6-pinion planetary, I went with the advice I got from George at Transfercases Unlimited to put fully synthetic Mobil 1 5W-30 in it. He refuses to warranty any NP231HD that he builds if it just had ATF in it. He claims that the chain whips up the ATF and it evaporates too quickly; the only reason the manufacturers use ATF is to save on gear oil and avoid the confusion of having one type of fluid in the transmission and another type in the transfer case.)