There is no appreciable weight difference between 92-99 SSEi'*. Nor much to speak of between them and the L67 SLE'*.
The only REAL difference is WHERE (what RPM) they deliver their power at. All 94/95 SSEi'* and SC/SLE and SC/SSE will run right around the 15'*, but the 94/95 will have better 60' times. 92/93 stock times lag slightly.
We didn't know much of this until this year, but now that we've had so many Series 1.5 cars run this year, it'* very apparent.
On the subject at hand, I believe you see the SC belt being shared by the Alternator. The reason for this is that they probably didn't have room for two belt paths. Think about that.