A shrill old-Left assault on the rising new Right; Friendly Fascism: The New Face of Power in America, by Bertram Gross. New York: M. Evans & Co. $15.

For over a quarter-century Bertram Gross has manned the barricades for a managed economy. The distinguished professor of public policy and planning at Hunter College and professor of politcal science at City University of New York first drafted Harry Truman's Employment Act of 1946.

His most recent creation was the Humphrey-Hawkins Full Employment Act of 1978 . In the interim Dr. Gross has labored in the vineyards of political liberalism by serving as governmental adviser to advance his philosophical causes, which he espouses in frequent literary contributions to The Nation and Social Policy.

Yet the salad days of liberalism are fast fading. The old slogans and programs are receding before the onslaught of a neoconservatism that has captured the attention of an electorate grown weary of rhetoric urging social millenniums. Things have become so desperate that free enterprise is threatening to make a comeback as the employer of first or second resort. This sobering prospect impels Dr. Gross to warn us grimly that this new face of capitalism is merely the prelude for the fascism threatening our future.

Little matter that political cycles have been part of our history. Gross argues that a divergence from the Democratic/liberal course this country has been pursuing for the past half century can only deliver the republic into the cluthces of a fascism even more lethal than the Hitler-Mussolini vintage, because ours will be so benign in initial appearance.

There are numerous flaws in the book. A case in point is the author's contention that the seemingly apparent absurdity of a fascist takeover is the greatest invitation for its actually happening. That is to say that we will not be ready for the coupm because the likelihood seems so outrageous.

But more to the point is the frenzied lack of focus of a book that flails the establishment for every national malady, from economic stagnation to drug abuse. Dr. Gross blames elitist corporate greed for desensitizing the body politic to the dangers of Friendly Fascism.

The consummate irony is the shrill tenor of his book. The footnotes bristle with references to Governor Reagan's "First Parafascistic State." This hysterical response calls to mind the author's admonition about the terrors of "McCarthyism." For lo these many years liberals such as Dr. Gross have rightly decried the recklessness that equates liberal ideology with communism. Now that the pendulum is swinging to the right it seems unfortunate that the liberals want to make "fascism" the new buzzword.

The political guard may change, but that hardly means the sky is falling, as Dr. Gross would have us believe.