Trust me, it happened.

He was a backup for both guard and tackle and was being groomed for perhaps left guard aftger Tom Mack retired.

But the Rams went another way. In 1979 they moved right tackle John Williams to left guard and jackie was the right tackle forever after that (except in 1981 when he played some left tackle due to injury)

But John Williams got hurt and the Rams had to put rookie Kent Hill in at left guard and the position was his.

Slater played guard in 1977 and 1978 (maybe some in 1976) in games when Rams had big lead---or if someone went down for a few plays.

But starting in 1979 he only played right tackle for rest of his career (with the 1981 exception when they though Jackie would be better at left and Doug Smith atr right tackle when Doug France and others went down).