The way I understand it, ATF+4 is a semi synthetic ATF that is
backwards compatible with any and all Chrysler transmissions.
Viscosity wise, I think all ATFs are about the same. The key advantage
with ATF+4 is the high heat handling capabilities. You could visit the
Valvoline web site and send an email asking for advice on which ATF
they recommend. Keep in mind that today's Dexron II and Dexron III are
also semi synthetic fluids.
The old A727 and A904s could probably live well with Dexron, or ATF+4.
Good Luck, Bill