I collect information (brochures, books, microfiche, etc) on the RWD Celicas but this is the first time I have heard of the Silhouette. From your description it sounds very similar to the GTA (automatic) and USGP (5-speed manual) that the US used to get rid of remaining stock. Since the Yanks are so good at trumpeting their stuff, I assume it must be a Canadian only package. The US/Canada microfiche doesn't mention it, so it is not from the factory. So it is probably either a dealer package or a Toyota Canada package.
Here are the US brochures.
http://members.iinet.net.au/~stepho/...8003-USA-USGP/
http://members.iinet.net.au/~stepho/.../80xx-USA-GTA/
You already mentioned the sound system (originally used in the Cressida) and the unique B pillars. Does it also have special interior trim, a special honeycomb grill and alloy 14x6" wheels (8-spoke that was also optional on the normal Celica or mesh design that was also optional on the Cressida)? Is it a coupé or liftback?
Do you still have it (or at least pictures)?
If so, can you send details of the build plate in the engine bay (specifically the build code that looks something like RA43L-BLMQSA) and the VIN. These often contain codes that point out options.
- Stepho