I went with the tunnel out of the front cut. it was probably a bit more work but is better in the long run. Jus cut out the old tunnel then sit in the motor and box. bolt up the new tunnel to the ca18 crossmember and the weld it in. My engineer didn't even notice that it had been done. that way the hole for the shifter is in the right place and the cross member bolts straight on. You will need to get some new carpet made though