Hire a company to perform a "skip trace." You can google it and find many companies who offer such services. It's generally not expensive to do.
This is not to be considered legal advice nor does an attorney-client relationship exist.
The costs to locate individuals or assets can run in the $1000s. You dont say how much the judgment is but you need to evaluate what is owed v. the additional costs in locating them. Was the judgment recorded in the counties where they own assets? Was the judgment docketed with the department of state? Have you tried to do the searches referenced by the other responder? Judgments have a 20 year vitality so you dont have much time left to pursue this one.
The answers given are limited to the facts as given and presumed by the answer itself. Without seeing actual written documentation or having a conference to more fully explore the issues, this short answer has only limited application. Make sure to seek legal counsel and provide all documentation to get assistance in making informed legal choices. Bstein@dcfsz.com, 305 377 1505
If the defendants names are not common, you may be able to find recent information from the clerk of court websites or the public records recorded in the county where you think they may be living. Another potential resource is the State of Florida website for searching businesses. That site is www.sunbiz.org and you can search by a company name or by the owners/officers of the company. Also, if the defendants are in a profession which requires some type of certification or license, you may check with the Florida Department of Professional Regulation. The site is www.myfloridalicense.com. Like the prior response stated, time is running out so act quickly whatever you do.