If it's a 3.54:1 diff they're all the same. It shouldn't rattle, the input pinion is supported by a pair of taper roller bearings, preloaded and seperated by a collapsable spacer. It should be nice and tight, the bearings have a measurable running resistance (this is how they are set).
I think yours is toast, good news, could it account for a strange noise you've been hearing?