Oil in my antifreeze?

[1Madmachinist]

So I dumped the oil an no signs of coolant. Dumped the coolant and after sitting for more than 24 hours there is no oil floating on top so I am assuming there's very little in there. I pulled the thermostat and the water pump and it looks like the water pump has either been off before or it has been changed because the gasket has already been cut. It has a plastic impeller (still intact) so I am changing it and the thermostat while I am in there. No apparent oil in any of these cavities.
I pulled the oil cooler off and the O-rings were completely flat and two opposing o-rings, an oil and a coolant port, were crumbly but not falling apart. Looked like an oil streak in between those ports but honestly that could have happened when I pulled it off.
So the flushing will begin and we'll see if the oil returns.
My question is the o-rings I ordered seem pretty loose in the trepan grooves in the top of the motor.
I have 2 PN 99970740940 26X3mm and 2 PN 99970738940 35X4mm and now I see a third size listed as well. Are those the correct o-rings?
Thought I saw another post with these part numbers listed as well.
Thanks,