If you're "retired" ask for a lump sum payout of your benefits including 401K, pension, any unused vacation and sick leave time, etc., etc. If you're now a "contractor" ask for a pay rate that includes the amount normally paid in benefits like life and health insurance, sick days and vacation days, and the copay for Social Security.
After I was bought out the company offered nearly double the amount I was being paid to come back as a contractor. It sounded good on the surface, but they wanted me to do things like shut down production facilities and move production lines from one plant to another prior to shutting down the plant the lines were removed from.
The money was good, but the jobs sucked. I spent more than 20 years trying to get the people in the production facilities to trust me, I wasn't going to undo that for a couple bucks. They bugged me to take the job for over 6 months, each time with more pay and incentives. I passed on the offers and don't regret it for a minute.