There's not a lot of info around about Manuel B. Holcolm, but thanks to the Soulful Detroit forum I managed to get more than I expected.
The are only two singles credited to Holcolm [this being the easier of the two to find], both on the Diamond Jim label, but there are as many as seven other singles by the group EJ and the Echoes on which Holcomb sings. It's not known who's playing on this record, but it's clearly not the Echoes as the group had broken up by this time. Holcomb and the band were from Flint, the label was out of Detroit. The year on this monster is probably '70 or '71.
For those who would like the instrumental track, I've included the b-side as well.