As linebacker Reuben Foster deals with an ankle injury, the 49ers are looking into some outside help. San Francisco auditioned linebackers Sean Spence and Donald Butler on Tuesday, according to ESPN.com’s Field Yates (on Twitter). 
Spence spent last season with the Titans and recorded 50 tackles with three sacks in 15 appearances (six starts). He hooked on with the rival Colts in March, but Indianapolis decided to eat the $750K guaranteed in his deal rather than keep him on the 53-man roster. Spence might not be starting material, but he could be a worthwhile reserve for SF until Foster gets back on the field.
Butler, a former third-round pick, spent his entire six-year career with the Chargers before being released by the team in March of 2016. He joined up with the Dolphins in September of last year and saw time in 14 games, including five starts. His 28 total tackles marked a career low and it was his first season without at least half a sack.