ok ive got a 99 pontiac montana with the 3.4 motor and a 03 pontiac grand prix with the 3.1,they are both going to eventually need a transmission,the montana is going faster than exspected,ive heard that the 3.1 and 3.4 motors are the same,just the top end id different,would a trans out of a 3.1 fit a 3.4 and what years cross reference with the 99 3.4 and which cross reference with the 03 3.1 or in other words wich years of trans fit the 03 3.1 and 99 3.4,thanks