Holden Hill Radiator Repairs, north of Adelaide
645 North East Road, Gilles Plains
8261 6173
$260 for a new aftermarket radiator

Finally! Was about the 20th radiator place I rang, and the first who could get hold of them. Had two separate suppliers for them (one at $260, the other at $286).
Still a bit on the expensive side, but it is at least realistic vs the $700 I was originally quoted.
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Took my radiator into a major (supposedly reputable) Adelaide radiator workshop to have a flush and clean. Four weeks (!) later having had no call from them, I phoned them today to be told that the plastic top tank fractured during removal and that:
1) they cannot source a new top tank,
2) they've never seen a radiator that small,
3) none of their suppliers even list a Suzuki Sierra (they tried telling me it must be fully imported!) and,
4) basically I'm left with no radiator and on my own to find a new one, unless I want to pony up for a custom copper core and bronze (?) tanks.
Anyone know where I can source either a new top tank or new radiator? Would prefer not sourcing from a wrecker if I can avoid it as it would likely be in similar poor condition to my own.
Cheers,
Tim