Turns out Sheldon played the last 31 games of his brief Big League career in 1977, hitting .203 with 13 hits over 64 at-bats while DH-ing and playing a few games out at second base.
It was a return to the Majors for him, as he spent all of 1976 in the Minor Leagues after getting some MLB time in both 1974 and 1975, albeit part time.
In his first taste of the Big Leagues, he appeared in 10 games during the 1974 season, collecting two hits over 17 at-bats for a forgettable .118 average.
But in 1975 he played in 53 games, batting a very nice .287 with 52 hits over 181 at-bats, scoring 17 runs while driving in 14 with three doubles and three triples.
I couldn’t find out why, but after his Major League action I 1977, he never even played any Minor League ball after that, finishing up his career with an average of .256 with 67 hits in 262 at-bats over 94 games.