Sump locating dowels?

[Stunned Monkey]

Hi all, coming back to reinstall my sump and I notice two of the holes are larger than the others, with a corresponding recess for a hollow dowel in the block. There's nothing in my tray of parts that looks like it belongs here, so would appreciate someone pointing me to what's missing, or to say "yeah, they stopped bothering with those in fairly short order". TIA

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