The Niners are set with starters for the 2002 season at every position except left guard, where the team would like to replace 39-year-old Ray Brown with Stone, who is rated by several observers as the top guard available on the open market.
The team's pursuit of Stone likely will be San Francisco's last dalliance in free agency until the Niners see how their roster shakes out after the two-day draft, in which they currently have nine picks.
"We feel like the only position that we don't have a bona fide established starter in today - if Ray Brown doesn't return to the team - is guard," Niner G.M. Terry Donahue said. "So that has got to be one of our concerns.