How can I find if Co. I worked for many years ago (they've since changed names) has a pension for me?

I worked at Washington National Insurance company. I don't know what the company changed it's name to after I left.How can I find if Co. I worked for many years ago (they've since changed names) has a pension for me?
you could contact the company with the latest name and work backwards!!!How can I find if Co. I worked for many years ago (they've since changed names) has a pension for me?
There is a foundation call the Pension Recovery Project which has answered questions like this for many people and recovered millions of dollars for them. It is funded by federal grants. They track down companies that have been bought out or who have gone out of business.
You have to work for a company for at least 5 years before you get a pension.