I have been to the local ford dealer in Windsor (NSW) and they have told me that there are different "K" crossmembers for the EB I6/ V8 and for the EF/L I6 and V8. The differences are where the engine mounts attach. Although the 6 and 8 EF/L look very very similar in eng mount holes.
A mate of mine has an ex race EL, was a XR8 and is now a XR6. Darren you know Danny's car.
So I'm guessing they had to change the crossmember for the engine change.
The holes for the chassis would be the same for EA to EL I would have thought. Out of interest, does anyone know the difference in mount positions for the EF/L 6 and 8???