I've done alot of HO coversions ( 2 were 96 obd2),, and 4.3 is right you gotta change it all. Don't even attempt it without a complete 96 model donor vehicle. The wiring is really easy if you mark it all,, and take your time. Not sure if the wiring on your trans is the same or not cause I alway's use the complete drivetrain when I swap....