Propshaft length

[dogwood]

I wonder if any of you with your engine/box and rear end in
can tell me the length of their propshaft.
From the diff flange to the face of the box input shaft.

I asked Ash, he said he thinks his is 644mm.
As you may or may not know,
I have modded the rear end to make the wheel base 25mm longer.
Now the engine is in I can order the new prop.
Measured it yesterday....635mm !!!!!!
Was expecting 670mm, not sure what's going on.

Everything else should be to the book.
So thought I would ask what lengths other people have.

Cheers