Review on Innovative Metra 70-1786 Radio Wiring Harness for Mercedes 94-04/Landrover 99-04 - Simplify Your Vehicle's Audio System Installation by Tom Tucker

I think that's the difference between buying from Crtchfield and Revain. Revain didn't give me a choice whether I had a Bose amp or not. (I don't have a Bose amp). They just assumed I had an amp and said "this harness will fit" but it wasn't properly connected to my non-Bose 2000 Mercedes E320. The RCA connectors are for connecting the preamp to the amp - had to cut the RCA ends and splice the speaker wires to use the built in radio amp. Also, the only pin in the right place on the power supply was ground. I ended up having to move the pins in the correct order and connect the 12v from the ashtray because my wiring harness didn't have it. So it really wasn't plug and play for this app, no matter what dishes I had.