The Eagles spent the vast majority of their money this off-season on an offensive line makeover, and they are about to get their first real glimpse at that investment.

Training camp will open July 26 at Lehigh University - and five days later, the pads will begin popping in the summer morning heat at the team's first full-contact workout.

The Eagles say the additions of Jason Peters and Stacy Andrews along with the return of Shawn Andrews, albeit at a new position, have made the Eagles' offensive line younger, more athletic, and better.

All that can be said for sure right now, however, is that the Eagles made the offensive line younger and different. The new mixture - with Peters at left tackle, Stacy Andrews at right guard, and Shawn Andrews at right tackle - must prove it is better than the ultra-reliable and equally successful group led by offensive tackles Tra Thomas and Jon Runyan.

Thomas and Runyan played 151 games together from 2000 through 2008, including 17 in the postseason. The Eagles' combined record in those games was 88-45-1 in the regular season and 10-7 in the playoffs.

Both were very durable. Thomas, who signed with Jacksonville as a free agent in March, missed just seven games because of injury during his 11 seasons in Philadelphia. Runyan, still unsigned after undergoing surgery on his right knee in February, never missed a game.

Despite their dependability, and the fact that the pass-happy Eagles allowed just 23 sacks and had the best sacks-per-pass ratio in team history last season, coach Andy Reid decided it was time for change.

"If you're fortunate enough to be with a team as long as I've been here, you're going to see those changes take place," Reid said during the Eagles' camp last month at the NovaCare Complex. "I guess the obvious statement is, you knew that Tra and Jon weren't going to play forever. No player does. They've lasted and played at as high a level as you can . . . but you have to keep your eyes open."

The Eagles started focusing on Peters last summer, when the 6-foot-4, 340-pound offensive tackle skipped training camp with the Buffalo Bills as part of a contract dispute. Let us know if you are interested in trading the big guy, the Eagles told the Bills.

Buffalo, with Peters still unhappy this off-season, decided to pull the trigger, and the Eagles landed a player that Reid described as the best left tackle in football, a bold declaration from a man who prides himself on saying next to nothing.

"He's got a chance to be [the best], he really does," Eagles general manager Tom Heckert said. "He's super talented. Last year, for most of the time, he played really well. There were a few games he didn't play really well, and whether that was from holding out, who knows?"

In addition to giving up three draft picks, including the 28th overall in this year's draft, the Eagles signed Peters to a six-year, $60.65 million contract. So what makes the former college tight end so good in the Eagles' eyes?

"He's just so big and athletic," Heckert said. "You don't find a guy that big who can move like he can. Most of the super athletes are just a little over 300 pounds. He's got it all and he can do it all."

Peters, 27, is clearly the centerpiece of the Eagles' reconfigured offensive line, but the health of the Andrews brothers on the right side will be just as vital to making things work. Durability was an obvious strength during the Thomas-Runyan era. Shawn Andrews, after missing much of training camp because of depression, was sidelined for the final 14 games last season because of a back injury. He has missed 29 games in five NFL seasons.

Stacy Andrews, meanwhile, is recovering from surgery on the anterior cruciate ligament in his right knee. He missed his final game with the Cincinnati Bengals last season and was prevented from working in team drills during the Eagles' off-season camps. The torn ACL didn't prevent the Eagles from giving Andrews a six-year, $38.9 million contract.

"We knew if he made it to free agency, we were going to try to sign him," Heckert said. "We thought he could play both guard and tackle, and we didn't know for sure what we were going to do with him. We knew he'd start for us somewhere."

Andrews, 28, will start at right guard and his brother Shawn, 26, will be a tackle for the first time since his college playing days at Arkansas.

The two leftovers on the offensive line are center Jamaal Jackson and left guard Todd Herremans. At 29 and with 56 career starts, Jackson has become the most veteran member of the Eagles' offensive line. As the center, he's also the man charged with making this a cohesive unit in time for the Sept. 13 season opener against the Carolina Panthers.

"The chemistry part of it is going to be a big challenge just because Stacy Andrews wasn't able to compete with us during minicamps," Jackson said. "But that's what training camp is for. I felt like Jason picked things up pretty good as far as how we do things on the offensive line. Him and Todd worked pretty well together on the left side, and I think Shawn is doing a good job."

Jackson said the Eagles' new-look offensive line is built more to run the football.

"We want the coach to have the confidence in us to run the football a little bit more," Jackson said. "I mean, we really have some road graders on the outside now, and we have some pretty powerful guys on the inside, too."

The Eagles say this offensive line is new and improved, but the old and departed had a pretty good run and will be a difficult act to follow.

"Now, it's all about getting out there when the live bullets are flying," Jackson said. "When you get into a game, that's when you see how a person is going to react to something."

Contact staff writer Bob Brookover at 215-854-2577 or bbrookover@phillynews.com.