Beovox S45 and S45-2 are closely related.
S45 has a composite backside with 4 fittings for mounting, S45-2 has a flush wooden black back with two
threaded holes for the wallmount/floorstand.
Furthermore, there are several different versions of the S45 and S45-2.
Different tweeters used throughout production in both type 6302 and 6312 also required
changes to the crossovers accordingly.
The woofer, however, was the same all the way.
All original S45/S45-2 woofers had rubber surrounds that seems to never deteriorate,
often found with factory talcuum powder still on them.
Wonderful woofer and speakers and despite their differencies, all versions are quite similar sounding.
The Beovox S45 (80's 2-way type 6427) had a quite unique (6,4ohms) woofer with
foam surround and was a completely different, and in most ears inferior, speaker.
Martin