According to Dave Kessler, whose shop was an authorized B&S dealer,
the 2001 Series and Medusa were pretty much the identical horns.
This is how he described them on the Kessler & Sons website:

The B&S Series 2001 is the predecessor to the Medusa.
For the tenor sax, the body tube is the identical design to the Medusa.
There are only a few minor differences in key design.
Here are the few differences we have been able to identify:

Series 2001: Low C/D# Cluster 2 Separate Rods. Medusa (Series 2006): 1 Split Rod Mechanism.
Series 2001: LH C#-B Rollers are 2 Separate Rollers. Medusa (Series 2006) 1 Roller; 1 Tilting Connector Roller.

  • Bb Tenor 015591 - Goldbrass Classic Bb Tenor 015591 - Goldbrass Classic
  • Bb Tenor 015689 - Goldbrass Classic Bb Tenor 015689 - Goldbrass Classic
  • Bb Tenor 015712 - Goldbrass Classic Bb Tenor 015712 - Goldbrass Classic
  • Bb Tenor Serial # ? Bb Tenor Serial # ?
  • Bb Tenor Serial # ? Bb Tenor Serial # ?
  • Bb Tenor Serial # ? Bb Tenor Serial # ?

Fatal error: Uncaught mysqli_sql_exception: Table './bassicsax_petepiwigo/kah_history' is marked as crashed and last (automatic?) repair failed in /home/bassicsax/public_html/pix/include/dblayer/functions_mysqli.inc.php:132 Stack trace: #0 /home/bassicsax/public_html/pix/include/dblayer/functions_mysqli.inc.php(132): mysqli->query('\nINSERT INTO ka...') #1 /home/bassicsax/public_html/pix/include/functions.inc.php(538): pwg_query('\nINSERT INTO ka...') #2 /home/bassicsax/public_html/pix/index.php(373): pwg_log() #3 {main} thrown in /home/bassicsax/public_html/pix/include/dblayer/functions_mysqli.inc.php on line 132