i took my lb7 engine out last week and just got the lly in today. i changed the engine with the complete wiring harness,ficm,ecm. i also took part of the wiring harness from the fuse box to the ecm and to the engine and 3 wires to the trans, to get the easies route because the trans plugins are different. i got it running today but my suriety light is on. so i guess i will have to pay gm dealer to reset the ecm. but everything seems pretty good.if anybody is going to do this i will be glad to tell you what you will run into. email. andrewmanthorne@hotmail.com