Correct, my comment was specific to the 99 model referenced in question
The 97-01 and then 02-04 (different seats* but similar config) are individual rider & pillion (or cowl) and from 05+ are single dual seat.
* Both rider and pillion seats look
very similar between 97-01 and 02-04 but are not
compatible fit with each other.
To fit an 05+ S3 seat to an earlier model would require the subframe and plastics (and more) from same also.
This is my brother-in-law's Sprint - it has Speed Triple lights (on a Hayabusa front end!) and standard Sprint tail/seat.
Although looks solo rider seat, that is indeed one long seat - on the Sprint, the cowl cover goes over
the stock full-length seat
Here's Sprint from same gen (not same bike) that shows the same full-length Sprint seat without its cowl