DEXRON II for automatic transmission and the transfercase
replaced by DEXRON III which was backwards compatible for the transmission, but for some reason not for the transfercase
Since it is no longer made and no longer made under licence...
The good news is that the newer fluids have a lot more science into what goes into them, for performance, longevity and protection.
The garage that rebuilt my 258 consulted with their supplier and decided upon Mopar ATF+4 (Chrysler) for my '86 (guessing: likely because the TorqueFlite is made by Chrysler), and it works fine.
Carguy87 liked the ATF+3 or ATF+4 for improved shifting
http://forums.amceaglesden.com/index.php?topic=39085.0Search amceaglesden to see what other's experience has been with what they've substituted the Dexron II with.
Trickier is what to use for the transfercase.