A couple of years ago I purchased some modern railways signs at auction. Three were large reflective white aluminium panels 70cm x 70cm with a location name followed by the words “Block Point” all in black capital lettering. Two of the signs were for the locations “Eucolo” and “Renton” which are both on the Port Augusta to Perth line. (Eucolo is between Pimba and Lake Hart, while Renton is between Kingoonya and Ferguson.)
The third sign is for "Illeroo" but I have been unable to find that location in any current online ARTC schematics.
The centre of the district of Illeroo (post code 5715) is about 30km directly west of Port Augusta.
Myall Creek runs through Illeroo and the Port Augusta to Whyalla line crosses Myall Creek about 35km out of Spencer Junction.
However, Illeroo isn’t really that far from Tent Hill, Hesso, etc on the Perth line, and so it could have also once been used as a name for a block section on that line as well.
Having come with the other two signs from the Perth line, I initially assumed it would have been from there, until I found the very tenuous association with Myall Creek which raises the (slight?) possibility of it being on the Whyalla line instead.
Anyway, I look forwarded to any information which people may be able to contributed to determine the location of Illeroo,