Okay diff hounds who has pulled apart an ED sedan 3.08:1 diff and had a look at the crown wheel for 0578 or 0575 ?

reason I ask is to see if 3.45:1 crown 0578 will slip in.
Has any one done it and do you have to change the pinion gear?

Now don't hold me to it, but as far as my knowledge spans, all the falcon diffs from early X series are 78 series.

However a 3.45 crown and pionon wheel won't fit a 3.08 housing.