Rear shock reducing kit sizing

[Gus]

Hi
I am getting a new fox float X2 rear shock.
I want it to be able to go on both my Merida E160s.
2018, and 2021 models.
They have slightly different diameter pins at the lower shock mount.
You can buy different sized ‘fox shox rear shock mounting reducer kits’, but I cannot find any information on what sizes suit these two bikes.
Does anyone know where to find this information?
Thanks in advance!
Gus

 

[Gus]

I measured the space for the 2021 Merida E160 shock axle = 40mm.
And it’s axle is 10mm diameter.

So go to online shop…
choice of 40mm or 39.88mm
What !!!?
do I want it jammed in or a 0.12mm loose?…which sounds still pretty snug?