Bolt size/pitch etc for a Stacker mounting

Greetings Brains Trust

After recently having a thoroughly pleasant time removing a towbar and
electrical from a donor S70 and installing into mine I am thrilled with the
build quality of Volvos!

However, I do have one request (and yes I am a lazy git). Can anyone out
there tell me what bolts I require to install a Volvo stacker bracket into
the prewelded nuts that are present on the left hand side of the boot/trunk?

I am kicking myself for not putting my thread and pitch gauge in the box of
tools when I drove 4 hours to remove and install said tow bar.

Would I be right in imagining it it most likely a pair of M8 with a 10 hex
head?

Cheers

Hammo