Auto.Trans.Interchange..98-00 to 93

I'm thinking of dropping in a lower mileage 98-00 2.0 and trans. into my 93.Interchange on tranny's is 91-6,98-01.Anyone know why they say 98 and later trans. won'tdo it? I'ldno..no big deal..guess I could scrounge around for a low mileage older trans and switch them when I swap the motor.It'ld just be easier to take out 98-00 motor and trans,ditto 93 and drop it all in at once.
Thanks..