Could someone tell me where to find the fuel distributor on a 1994 C280?

Is it a dificult part to work on? I want to check the "o" ring on the shaft for integrity. It's hard to believe that such a small part could cause me so much grief. But. I guess it was a faulty "O" ring that brought down the Shuttle.

I ask because, thanks to RPM55, I performed the simple fuel leak check first; that is to remove the line from the fuel pressure regulator and check for gas.

This check proved negative. No Gas in the vacuum line.

I'll appreciate feedback. Thanks!