"Where are the Gang of Four now?" a Peruvian visitor asked Chinese Vice Premier Li Hsien-nien this year.

"When our foreign friends ask us that same question," Li replied, "We tell them that the four of them are well, they eat well and sleep well. And if they ask us where they are, we tell them that they are in the People's Republic of China."

Mao Tse-tung's widow, Chiang Ching, and the three top leaders of Shanghai, Chang Chun-chiao, Wang Hung-wen and Yao Wen-yuan, were all arrested a year ago, shortly after the death of Mao, their apparent protector. Their pictures have been airbrushed out of old photos and their names dragged through the mud.

But conversations with Chinese Communists here and in China suggest that all four are alive and living as comfortably as can be expected. None has yet been dragged out for public denunciation meetings. As far as is known, they are thought to be living under heavy guard in the same exclusive Peking neithborhoods where they once reigned as four of China's top six leaders.

But, sources in China say, they are also undergoing the usual Communist routine for purged officials. They must regularly read the official press, particularly articles denuncing themselves. They must undergo long interrogation about their associates and past activities and must write and rewrite self-criticisms.

They are unlikely ever to have a formal trial, but like Watergate convicts in the United States they may be sent eventually to a relatively comfortable work camp for former high officials, where their successors in the Chinese leadership will never have to hear from them again.