Well, I hate to say it but judging by the oil pressure fluctuation I gotta agree (partially) with your mechanic. At anything over 2K rpm the gauge should remain pegged. It's definitely a bearing problem. I'd guess rod bearing instead of crank bearings but the end result is the same. The crank needs to be machined.
Hard cheese old man. I'd take JMela's advice and hook up with the Benz Dr. He can probably line you up with an engine.
Man, oh man! An un-cracked dash! I didn't think existed! I just figured they were fairy tales!
