Squeal on 993 C4S

[trevor-uk]

Can anyone tell me where the short squeal is coming from when I change down, most often from from 4th to 3rd (slowing down, not getting ready to take off). It's had a recent complete clutch and dm flywheel (2k miles), could it be the thrust bearing (it was replaced)? It seems to let out a short squeal just as the clutch fully engages. It doesn't do it every time and I've never noticed it changing up the box.