This is the 20-position plug that connects to the SVX factory AM/FM/Cassette unit. There are 15 wires, with the same EIA-standard color-coding as other after-market harnesses. The wires also have text labels (for example, "Left Front Speaker +") and pre-stripped ends ready for you to crimp or solder. The 15 wires are:
Note: The SVX also has a separate 2-pin plug that connects to the factory CD player for illumination (see this picture). I am still looking for the correct shell for this 2-pin plug. However, I can include two extra wires with contact pins for an additional $1 when ordered at the same time as the SVX reverse harness. If you want this, please ask when you place your order.
For more information and testimonials from satisfied customers, see this post on the Subaru-SVX.net forums.