SANTA CLARA -- Leonard Davis has started every NFL game he has ever played. That's 155 starts, which includes a stretch of 64 straight games from 2007 and 2010. But what the three-time Pro Bowl guard wants starting with Friday night's preseason game against the Vikings is snaps -- as many as he can get."For me right now, as much as possible," Davis said. "I got to get out and play and get comfortable, and right now, it's not like I've been here, been around and know the system. . . . For me to go and play this preseason that is going to mean a lot for me."Davis signed a one-year deal with the 49ers the day veteran players reported for training camp. He has been cramming to learn the offense in the 15 days since."It was tough at first. We were doing a lot of installation, and what was crazy was we had to do an install and then I'd have to kind of learn everything from that day, and then the next day we're doing more, so it was kind of piling up. I was getting a little frustrated a bit at first," Davis explained. "I've ran all the same plays, but it's just a lot of nuances and how we go about executing plays. But from where I was from when I first got here to where I am now it's a big difference. I'm more comfortable with it now."Up until the 2011 season, Davis had never started fewer than 14 games a season, including all 16 regular-season games his rookie year in 2001. It is not hard to understand why. Head coach Jim Harbaugh described the 6-feet-6, 355-pound Davis as "probably the largest man I've ever stood toe-to-toe and knee-to-knee with in my entire life." He dominates with his size and strength. But his drive to keep learning and improving while he competes with Alex Boone to be the starting right guard, has impressed his quarterback."There are many guys that have played as long as he has that have a lot of egos especially when it comes to preseason," Alex Smith said. "A guy that's been the starter, been to Pro Bowls and all of sudden he's not in that role anymore. It's hard for them to handle that. He's a guy I really feel like checks his ego and just comes to work every single day no matter what's asked of him. . . . Whatever it is, he's willing and wants to get the reps and take advantage of it.""My thing was knowing the offense and getting as comfortable with it as possible," Davis said, "And also, while doing that, striving to work on technique and being conscious of what I'm actually doing and how I go about executing assignments."The only down year of Davis' career came last season. After starting 16 regular season games and one playoff game for the Cowboys in 2010, Dallas released him before the start of their 2011 training camp. The move reportedly saved the team 9.5 million in cap space. The Lions signed Davis halfway through the season but never activated him for a game. When a player with as much game experience as Davis misses an entire season, questions begin to arise over his future production. He worked during the offseason to provide answers.Davis is currently 20 pounds lighter than he has ever been in his career. He also underwent offseason foot surgery from which he is now completely healed. Physically, Davis feels good. He has no problems other than the usual nicks from practice. He is ready to prove himself, ready to be a starter again and ready for the usual nicks that come from taking snaps in a game. As many as he can get.