using valvoline dexron III here. thats what Chuck at FLP suggested.

 

It's an old racer trick from way back. Old Ford trannys,(C4-C6) needed to use type F because it has added friction coefficients in it. Putting it in a GM vehicle used to firm up the shifts, ie: shift kit in a can! ;D

Surprisingly though, most aftermarket rebuilders I have noticed are INSISTING on using Dexron III ONLY.

Don't really know why.

 

My 99 has synth in the rear diff from the factory also.

I use regular DexronIII in the trans.

 

royal purple-engine
reg dex3-tranny--jag performance
diff-penzoil-90w--

 

mike kurtz at century told me castrol type f. guess each builder has his own oppinion. mine shifts firm and is holding fine