After three years in the trenches, the troops of China Beach are finally coming home for good. On July 22 at 9 p.m., ABC will broadcast the last episode of the Vietnam drama, a two-hour show set in part at the Vietnam Veterans Memorial in Washington, D.C. ”We’re going out with the best episode we’ve ever done,” says John Sacret Young, cocreator of the show. ”It takes place at a reunion in 1988, where all the characters are interviewed about their experiences during the war. It’s an extraordinary episode, summing up a lot of things” — such as who got married to whom and who had kids. The award-winning but low-rated series was put on hiatus last winter, with the final seven installments remaining unseen until this summer. ”It’s a perfect ending,” says series star Dana Delany, who won an Emmy in 1989 for her performance as nurse Colleen McMurphy. ”It ties everything up. I’ll miss McMurphy — she was a great broad. But I’m glad it’s over. It’s time to move on.” To what? ”I’m shooting a movie now about nightlife in New York. I play the ex-girlfriend of a drug delivery guy.” And what’s next for Young? ”I’m still in the grieving stages over the show,” he says. ”But I’m directing a film. It’s an ecological horror story — part China Syndrome, part Chinatown. It takes place in the storm drains under Los Angeles. It’s a lot different from China Beach.” Key word here seems to be China.