'The Ink Truck': Pulitzer winner's forgotten first novel; The Ink Truck, by William Kennedy. New York: The Viking Press. 278 pp. $15.95 .

''The Ink Truck,'' William Kennedy's first novel, was published in 1969. Critics were good to it, but book buyers were not, and it sank. Now it is back, reissued and riding on the heels of Kennedy's recent large successes. ''Ironweed'' won the Pulitzer Prize and the National Book Critics Circle Award for Fiction, and his other Albany novels - ''Legs'' and ''Billy Phelan's Greatest Game'' - are bought and read enthusias-tically.

''The Ink Truck'' is a good book and an interesting book (especially for those who want the full evolutionary chart on Kennedy), but it is not in the same league with his later work.

Kennedy's first novel is, primarily, the story of Bailey, a newspaper columnist leading an extraordinarily unsuccessful strike. He is a man of enormous vitality, with appetites (for women, for life) reminiscent of Saul Bellow's Henderson.

''The Ink Truck'' starts rather simply but becomes zanier as it proceeds, and ends in some strange, comic, and surreal orbit that resists description. While reading this novel is necessary to understanding Kennedy's full range, only the most persevering of Kennedy's fans will find it engaging.