Did you completely disassemble, clean and grease all the bearings in the
suspension pivots? That is a common problem, and it doesnt hurt to make that
either an annual or 10000 mile servicing. It is also the front is squeaking.
The stock front shock has been known to squeak from the rubber wiper between
the two chrome outter covers. It has also been mentioned before that the
upper pivots tend to dry out on the front suspension. Perhaps having someone
stand alongside your bike as you bounce the suspension will help isolate and
locate the source of the noise.
RSRBOB