ATF+4 will work fine, but that recommendation is decades-old info, obsolete. Dexron-VI (the latest Dexron) is better than ATF+4 in pretty much all the ways that matter to shift performance, hot- and cold-temp performance, viscosity stability, resistance to foaming/oxidation/sludging/varnish, etc.
See attached tech paper, with this breakout list of the compared fluids:
A: Dexron VI
B: Chrysler ATF+4
C: ZF factory fill
D: Honda Z1
E: Toyota WS
F: Ford Mercon 5
G: Allison Transind