Aust LP2 bracket??

[Darrin Wright]

I have a LP2 Bren Gun Carrier (made by Newport Workshops) that has an odd bracket in the right rear of the hull where the Vickers ammo boxs are positioned, never thought much of it- after war add on by a farmer. Then a friend of mine found a carrier hull with the same bracket in the right rear of the hull which has now got me thinking, what is it used for?
The brackets are circles in blue (hopefully it will show/be able to be seen!!)
The brackets are positioned in the hull so that if a tool/equipment was placed in the bracket the Vickers ammon boxs would not fit.
Both carriers are from the Northern Territory and have been in service with the Army in the north.
Any idears would be appreciated, when I get to restoring the carrier I will probly remove it unless there is a reason for it being there.
also to note in the photo is the well made hand rail, possible for people to stand in the back for vehicle mounted parades, maybe Kangaroo shooters but it is too well made.

Thank you for any replies and putting me out of my misery!!!