Hyundai psf3 is basically atf dexron II, and you can use any dexron IIi or VI rated atf in it.
However if you are adamant and hellbent to use dexron II original color and spec psf, you will have to visit a mercedes parts shop and buy the febi branded yellow psf, (make sure its the yellow/amber/light brown oil and not the green one)
I personally fill older hyundai, toyota etc with mercon V atf, works a treat, however if customer wants the amber type, it gets the ac delco or the febi stuff or the mercedes stuff,
For offroad use I use a light hydraulic oil and make sure it has a large cooler for it too.
What is causing your car to fail its oil seals? Is the mechanic tearing up the center seal by dragging the rack teeth on it? Or is he messing up the teflon rings on the valve body?