Transmission fluid spewing from the fill tube

I have a 1993 k1500 suburban that the transmission was swapt for a good used tranny. Everything works, shifts fine and all that but when I drive it, tranny fluid spews from the fill tube and I noticed the dipstick is in a pop up state from where it sits. I dont know what could be the cause of this and I hope that the tranny isnt shot:( please help!