Here are the Eagles' 12 primary running backs from 1966 to 1975. There were quite a few others (such as 1967 #1 draft pick/bust Harry Jones), but these below are all the starters.
We start off with the tandem of Timmy Brown and Earl Gros. Brown played for the Eagles from 1960-67, and was their starting halfback from '62 to '66. Gros was the starting fullback for his 3 seasons with the Eagles (1964-66).
After backing up Brown and Gros in 1966, Izzy Lang and Tom Woodeshick took over as the starting backfield for '67 and '68. Woodeshick led the team in rushing from 1967 to 1969.
Leroy Keyes was the Eagles' #1 pick in 1969. [After an 0-12 start, the Birds won their last 2 games, thus blowing the chance to draft O.J. Simpson.] After a serviceable rookie season, Keyes had an awful 2nd year, then was moved to strong safety for his final 2 seasons with the Eagles. Leroy was 2nd in rushing behind Woodeshick in 1969.
After 2 seasons as the #3 back, Cyril Pinder led the Eagles in rushing in 1970, teaming with rookie fullback Lee Bouggess. Woodeshick and rookie Larry Watkins rounded out the top 4.
Pinder was traded away after the 1970 season, leaving Bouggess as the team's top rusher in 1971. He was joined by halfback Ron Bull, who played his final season with the Eagles after playing for the Bears from 1962-70. As in 1970, Woodeshick and Watkins were the 3rd and 4th backs.
With Bouggess lost for the season due to injury, Bull retired, and Woodeshick traded, the Eagles featured a new set of backs in 1972. Rookie Ron "Po" James led the team in rushing, with Larry Watkins sharing the fullback job with ex-Saint Tony Baker.
James' time at the top was short, with rookie Tom Sullivan taking over the starting halfback job for the next 3 seasons. Sullivan would lead the team in rushing from 1973-75. Norm Bulaich joined the team in 1973, and was the starting fullback for his 2 seasons in Philly ('73-'74). James was the #3 back for the '73 and '74 seasons.
In 1975, Sullivan had a new running mate: Art Malone was brought in from Atlanta as the fullback. Rookie James McAlister was #3 with Po James at #4.
When Dick Vermeil was hired for the 1976 season, he cleaned house at several positions, including running back. The only holdovers from 1975 were Sullivan and McAllister. Rookies Mike Hogan and Herb Lusk were in the mix, plus newly-acquired veterans Dave Hampton and Bill Olds.