To answer your question, Yes, the GenII engine will fit. Same frame.
However, like Sparky is saying, the change over will ensue a huge and lengthy headache if you aren't fully prepared.
GenII onto GenI -
- 1) You will have to run all GenII ECM/harness/sensors to operate dual butterfly throttle-bodies.
- 2) Since running GenII harness, unless you devote huge garage time to re-pin, you will have to run GenII gauges.
- 3) Since running said gauges, you will only be able to fit the GenII inners and body panels to groove with GenII gauges.
Sound fun?
Now to land your 2006 engine into the GenII? Yes,,, if you change out the ECM. Then you have to work backwards to take out all that won't work with GenI ECM's Capeche? Mess ensued!