I had the rear shock on my 900 overhauled and a new bottom bush fitted by UK suspension in Bradford. It only cost something like £75 + VAT whch was way cheaper than a new shock.
A new rear shock from Ducati is £525
A shock from any carbed 900 or 750 will fit straight on. The shock from an i.e. model will fit but it is about 12mm longer which will quicken uo the steering and improve the ground clearance. Quite a few owners do this mod apparently.
All the other Ducati models, Monster, ST, 916 etc use a linkage and tie rod so the shocks ae no good for the SS models
Should you decide to get it rebuilt, UK Suspension's details are:
UK Suspension
Unit 6/7 Birksland Industrial Estate
Birksland Street
Bradford
BD8 8TY
Tel: 01274 305671