He was an all-city, all-state and All-American running back as a senior at Toledo's DeVilbiss High School in 1962.

"[3] In 1964, Detwiler was part of Bump Elliott's Big Ten Conference and 1965 Rose Bowl championship team.

The Wolverines narrowly missed a National Championship in 1964, in part due to a critical fumble by Detwiler into the end zone in the team's only defeat, a 21-20 loss to Purdue.

[5] Both teams were in the Top 10, and Detwiler scored on an 18-yard touchdown pass from Bob Timberlake in the final minute of the first half.

"[2] In the 1965 Rose Bowl, Michigan beat the Oregon State Beavers 34-7,[6] and Detwiler had a 30-yard reception from Timberlake on a key scoring drive in the third quarter.

[10] Detwiler was named to the first-team All Big Ten team,[11] and he rushed for over 100 yards in the Blue–Gray Football Classic in 1966, earning himself the game's most valuable back award.

[12] Detwiler was part of a class of six NFL draftees from Michigan that year (Mike Bass, Frank Nunley, John Rowser, Rick Volk, and Carl Ward).