SPCR

I have some 40mm Closed Chassis fans that are 28mm thick but i cant seem to fin any anti-vibration mounting hardware for them at all?? any suggestions outside of a rubber gasket??

28mm thick 40mm fans are an unusual size. I doubt these fans are particularly quiet. You can adapt closed corner fans to take anti-vibration mounts by cutting away the corner sections with a hacksaw or a set of pliers. I've done this before.

I doubt that you'll get much in the way of silence cooling with a fan that small as they tend to run at very high RPM's. Is this for a small form factor PSU perhaps? Any kind of mod to get a bigger fan in would likely to be of more benefit than soft mounting the 40mm.