I was thinking of using a 71 series behind the a series
and wouldnt really need the strength of the cast iron SW
so in this case Rosanne Barr is the cast iron one ready for
a Walrus donger while Miranda Kerr is the alloy one which
will suffice the lesser abuse of an A series?
(less abuse as far as we know anyway)

I feel like a twit not even thinking about other 71 series
boxes from the bluey especially! thanks fellas :)