Non ATF+4 in a A500 trans..?

As I've been told & followed so far an A500 (904+o.d.) only should have ATF+4 fluid, right?
Well I'm in trouble now; I'm stuck out of reach for ATF+4 & have to drive the car & myself away from where I'm at & the only trans fluid on the shelves here is normal ATF for some gm product that's been left behind...
So my question is: What can or will happen to my trans if I use normal ATF?