Here are most of the Eagles' starting linebackers from 1966 to 1975.
Dave Lloyd was the Birds' starting middle linebacker from 1963 until 5 games into the 1970 season, when he was replaced by Tim Rossovich.
Mike Morgan was the Eagles' starting left linebacker from 1964-67.
Harold Wells (no card) was the starting right linebacker from 1965-68.
Adrian Young was the Eagles' #3 draft pick in 1968, and played left linebacker from 1968-71, although missing most of 1971 due to injury. By the way, that's not Young's picture on his card. It's Eagles' 1968 punter Rick Duncan.
Ron Porter was acquired from the Colts in 1969, and was the starting right linebacker for 3 years, and the left-side starter during his 4th and last season with the Birds.
Tim Rossovich was the Eagles' #1 pick in 1968. After 2+ seasons as the starting left end, he moved to MLB after 5 games in 1970, and remained there through the 1971 season.
Steve Zabel was drafted as a tight end in 1970. He moved to linebacker in his 2nd season, and was a starter for his last 4 seasons in Philly - mostly on the left side but occasionally filling in at MLB.
After Rossovich didn't pan out following 1971, the Eagles brought in a host of middle linebackers in 1972. Ex-Charger and Steeler Chuck Allen started 8 games in '72, while Zabel started the other 6 games. (MLBs Dick Absher and Bill Cody worked on special teams.)
In 1973, Allen, Absher, and Cody were out, and ex-tight end Marlin McKeever and Dick Cunningham were in. McKeever made 11 starts in the middle, while Cunningham started 2 games. (I can't find my 1973 Dick Cunningham card, so my new Fred Whittingham 1966 custom card is filling in nicely!)
The Eagles finally put an end to their 4-year middle linebacker carousel by trading for Bill Bergey prior to the 1974 season. Bill solidified the middle for many seasons to come.
Frank Lemaster and John Bunting played on the wings, giving the Birds a nice linebacking corps, something they were missing since Maxie Baughan was traded after 1965.
(When Dick Vermeil arrived in 1976 he went to a 3-4 defense, with LeMaster moving inside next to Bergey.)