High pitch rattle rear end or U joints??

[scubaclimber]

I have this high pitch rattle kinda of a ting ting sound coming from my rear end. I just had the rear end overhauled new halfshafts, ring and pinion(took 6 teeth off my old one) and eaton posi track. done by a good shop. one guy told me to replace my u joints. Are spicer u joints worth the trouble to get? and does a bad u joint make that kind of sound. or should i be more concerned with my rear end 10 bolt fyi