I have a 2004 Enduro which has a very annoying knock/crack sound from I think the suspension, as if something has moved slightly. It only happens about 5 or 6 times during a ride.The shock/bushings are brand new (Float R) and it had new main bearings about 3 years ago. The BB seems ok, so apart from possibly the rear hub should I get the whole bearing set replaced? Don't really want to do this unless really necessary as it's £80. The bearings otherwise don't seem to have any play. Any ideas much appreciated as it's driving me nuts!

check chain stays

Thanks Jedi, should I check the bearings at either end of the chainstays then?

yeah and main pivot.

^^^^
THIS

I've seen the chainstays on an Enduro snap as a result of seizure (caused by lack of correct maintenance). Definitely check everything moves as it should.

dont need to go the whole hog with a bearings set, take the whole rear end apart and check each bearing individually – replace any that are rough

mine always went, main pivot then chainstay then seatstay/linkage

3 years is a long time for a set of bearings.

Lads I ride with replace theirs Spesh bearings every year.