ML350/370G4 Duplex BackPlane on an ML350G3?

[R.Padalsky]

Having seen in 2006 for the 1st time the 339323-B21 Duplex Backplane in the maintenance doc of ML350G4 I installed it to split successfuly the hot plug cage into 2+4 hdds on a 642 SmartArray controller.
Now looking at an older server ML350G3 (with only 2 HDDs on a 642 SA card) whose hotplug cage looks similar I wonder can I use the same duplex backplane to add 4 hdds to the 2nd 642 channel?
Since the servers are in different places and it is time consuming to open them up for comparison I tried to discover a hint for the applicability for the G3 server but didn't find an identical section in the G3 maint.guide to compare to the G4 guide. The drawings in the 2 guides are looking very similar but no clue of connectors compatibility and the like. Anyone stumbled across or tried already the approach? Pls. comment.