Dexron III is the correct replacement for Dexron II which is now obsolete. Actually, Dexron III is a Dexron II/synthetic blend and is a superior fluid. For even better protection/performance, you could use a full synthetic ATF such as Amsoil, Redline, Mobil 1, Royal Purple, etc. They can be inter-mixed with your existing Dexron II in any ratio.