Re: Falcon six
Not necessarily. The 4.0 motor was released with the EB II. EA and EB I Falcons were offered with MPEFI 3.9 motors from the start. Therefore there are plenty of MPEFI 3.9 motors around.
Also, the 3.9MPEFI motor put out 139kw while the early 4.0MPEFI motors put out 147kw.
As far as I know, the MPEFI system on them is the same EEC-IV system. Although there are probably minor calibration differences between them.
468 Big Block Dragster