replacing trans fluid in a '54 Kaiser with dual range hydramatic

[retroguy]

I'm getting ready to change the trans fluid in my hydramatic as I'm sure it still has the original fluid.  I'll also drop the trans pan to see what the screen and bottom of the pan look like.  I've found a replacement gasket at Fel-Pro Permadry--molded rubber silicone one piece construction with a rigid carrier for durability and fit.
     I'm uncertain about the right trans fluid to use.  The original fluid was type A ATF which is mineral oil with additive to reduce foaming.  Articles on line say that Dexron !!! or V! synthetics are much better fluids and are compatible with original type A.  But I've also seen comments saying to not use synthetics in '54 hydramatics.
     What experience and recommendations are out there regarding the best fluid to use in an old transmission?

[rialto]

I used old fashion nonsynthetic Dexron II in my 54 Manhattan. I avoided the newer hi tech synthetic fluids. There is no telling what those new chemicals could do to a sixty year old transmission. Many of them didn't exist when the transmission was built.

[retroguy]

thanks.  The new fluids sound great but I also worry about their affect on my transmission