Regular production
Testarossa - Prototypes
512 TR - Prototypes
F512 M - Prototypes

Official specials
512 TR Speciale
Mythos
Testarossa Spider

Non-official specials
Bizzarrini BZ-2001
Colani-Lotec Testa d'Oro
Pininfarina F90
Pininfarina FX
Sbarro Alcador
Zagato FZ 93

Spider conversions
Coachbuilder
Design & Technic Ltd.
EBS
Eurotech
Lorenz & Rankl
Metalcrafters
Pavesi
Pininfarina
Straman
Ultrasmith

Tuning
Berlinetta Motorcars
Gemballa
Hamann Motorsports
Koenig Specials
Lotec TT 1000
Norwood

Other
Miami Vice
Racing

Coachbuilder

At this moment, there is not much known about this company that made targa/spider conversions of the Testarossa.