Trans fluid recommendations?

Can any tell me what transmission fluids are suitable to use in my '87 300D.I live in a VERY rural area of upstate N.Y. and can't drop by my "local" MB garage for a quart.The car has 113k on if and is running flawlessly.I just want to keep a qt. handy.You never know when a small leak might develop in this cold N.Y. weather. My owners manual say DexronII.I've only heard of DexronIII.Is this what they are referring to?
Also the same goes for the brake fluid.I was told to only use MB brake fluid.Is there any thing else compatible?
How about power steering fluid? Same thing...?
As I said before,it's like,an hour drive to the nearest MB dealer.I suppose there are numerous web sites that I could get whatever I need.And probably genuine MB stuff too.I am not partial to on-line purchases.The less I use my credit card the better.Thanks for all the help.J.S.