I believe you can use gen 3.5 struts, but the difference is that the gen 3 struts are serviceable and the gen 3.5 struts are non-serviceable. From my understanding it means that a gen 3 can use struts for a gen 3.5 but if you do you can't go back to gen 3 struts if you decide to replace them again (if I am wrong, correct me please).
As for the differences in parts, in the manual it notes that the gen 3.5 models have a bearing and upper spring seat while the gen 3 doesn't (for the 2 front struts). But maybe this link will help:
Gen3 Front & Rear Suspension OEM parts number!
But hopefully someone else can give a bit more info
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1992 Toyota Camry LE 5SFE 4 cyl. 2.2L
A.K.A. "Ron Burgundy"
198,000 mi. (as of February 9th, 2010) and counting