From what I've read, Matic D is Dexron III so does that mean I can use Dexron VI which is supposed to be backward compatible to D3 and is a superior fluid? I have plenty D6 at $4 a quart but I can get Matic D from the dealer for about $1.60 a quart.
I'd save the Dexron VI for applications that really specify it. You sure about that price for Matic-D ? That sounds REAL cheap. I know you can safely use a universal fluid like Castrol Import Multi-Vehicle for Matic-D (and up to -J).
Plus, the additive package that is being used is a more modern version and makes for a more stable ATF in terms of friction retention, shear stability (viscosity retention), and improved oxidation inhibition than any Dexron III/Merc or Matic D.