Lots of substitutes can be used in place of J-matic. Don't be brainwashed into thinking that OE fluid is the only choice.
Pennzoil, Amalie, Amsoil, Idemtisu, Castrol, RoyalPurple, Schaeffers....as well as a bunch of other companies, make equivalents.
J-matic is simple HMF'd for smoother shifts and TC cycling, along with being a blend for more consistent all temp performance. At the dealer price, I would avoid.