I worked from 1979-1989, there have been numerous takeovers, and I have contacted some many companies, and no one seems to have any information on me.
That's a tough one...What type of plan was it? What's the newest of the companies? If you know, you can plug it in to the 401k ratings directory on this site and look up the custodian where your funds are being held. You may also want to check with your state's unclaimed property department: icash.illinois.gov/