One of President Reagan's staunch conservative backers, kitchen cabinet member Joseph Coors, landed an appointment in the administration when Army Secretary John O. Marsh Jr. named him civilian aide for Colorado.

The task of a civilian aide is to let the home folks know what's going on in the Army and carry their opinions back to the secretary. The job doesn't pay much--in fact, it doesn't pay anything, except expenses for a once-a-year trip to Washington for high-level briefings at the National War College--but it does give Coors access to information on Army policy, as well as access to the secretary's ear.

Another of Marsh's civilian aides, one of five holding "at-large" appointments, is Frank Barnett of New York, the hawkish president of the National Strategy Information Center, who was a member of candidate Reagan's military advisory board and later served on the president-elect's defense advisory committee. A spokesman for the civilian aide program says, however, that the positions aren't considered political slots. "We keep politics out of it, to the extent that's possible."

The Army secretary has at least one such aide in each state (more in the heavily populated states). Marsh has announced a dozen of the two-year appointments since April, and has several more waiting.