Two capacitors and two resitors right? It's been a few years since I've done any work off schematics and being in the Army the last 6 1/2 years hasn't helped me out in the brains department much. But your right it's seriously pocket change for the parts! I didn't even know about the cheapy Ecklers one untill I found this thread so I was looking at the 50 dollar replacement variety I was also under the impression that you needed this part otherwise your tach would burn up. My tach wasn't working anyways, I was just curious about what this component actually did and why it cost so much. I'm all about helping others so hopefully this will save someone some heartache.