Atf for 904/999 transmission

Im about to replace my transmission pan gasket for the 4th time at 8 dollars a quart atf4 is getting really expensive can I use the cheaper dextron stuff or should i stick to atf4?

If you are dropping the pan just for a gasket change and if the fluid doesn't have many miles on it, why replace it with new. Drain it into a clean pan and put it back in.