96 chevy 1500 motor swap 5.7 vortec

[fly-esr]

k i put a 5.7 vortec motor out of a 99 gmc yukon in a 96 chevy 1500
i am having a problem getting it to fire to the plugs
i was told that the yukon had a security ignition that the 96 doesnt have and i was wondering if that was true
if so i was wondering if there was a way to by pass the security
i am using the computer and wiring out of the 99 yukon
i am lost and need some kind of help