Hopefully the VIN will help you with the code!

You will absolutely need an amp. You're right that the connectors match, but there will be no sound without the amp. I guess they had to stuff so much into the SC901 radio that something had to be left out.

What is this SC901 coming out of?

The C70's generally had the amp in the left side of the trunk. Making those amps work in a S70 or V70 is possible but requires some rewiring.

If the SC901 is from an S70 or V70 - the amp should be under the passenger seat and the Dolby decoder is behind the dash. Make sure you get the wiring harness for the amp since they are no longer available from Volvo.

The 850 series and T5 70 series cars with something other than the SC901 originally would have the amp behind the radio.

The Dolby decoder was always installed behind the radio.

Regardless of what is behind the radio, get that mounting bracket too! Another part that is no longer available from Volvo.

More light reading ...

http://www.matthewsvolvosite.com/forums/viewtopic.php?f=1&t=30204


My setup features an amp from a 850R so it mounts behind the radio. I have the Dolby decoder shoehorned into the area to the left of the glove box liner. There are no issues doing this if you can't find the proper underseat amp.