Centre diff needed for 99 Legacy B4

[johnoirl]

my chassis plate says ive a ty754vbaaa gearbox. which i believe is 4.44 ratio.
im looking for a centre diff as i think mine is on its way out.
How can you tell the difference in a box by looking at them, ive looked at a few gearboxes and i couldnt see any serial numbers etc.
Cheers

 

[BazGF8]

Number is on the side of it beside the starter

 

[davelegacy]

There is only x2 centre diffs.

1:1 drop ratio.

So one box normal looking rear casing. One box rear casing has square plate on top.

Have a box with front diff whine.

Can spilt for centre diff if needed.