Or if all you have is a New Holland dealer local (like I do), Master-tran is the exact same thing as Hy-tran but with a New Holland label.
As far as other fluids aside from what was recommended above go, just pick a good quality fluid. You don't HAVE to have hy-tran/master-tran but in the long run, you get what you pay for. Biggest different is it can absorb liquid, saving potential wear and tare on your transmission.
I used a different type of fluid in my gear 1050 and it works just fine but next fluid change, I want to go back to master-tran just for peace of mind. Other people have had good luck with Tractor Supply brand fluid. It's not like putting a different fluid in your machine will make it go boom, just use good judgement and you should be fine