The hub is currently qr to convert to 142×12 shimano, is it a case of just changing the end caps (push fit?) or do you need to change the axle as well?
Thanks.

Just end caps

It depends in the age of the hub. I have a 240 that predates 142×12 and a 350 post 142×12. The axle in the 350 accepts the 12mm axle, the pne in the 240 doesn’t.

So I can just pull out the end caps and measure the diameter of the hub axle to see if the 142x12s will fit in?

I think all 350s will have the more recent 12mm axle. But yes, easy to check.

cool cheers.