Officials at the National Highway Traffic Safety Administration say they are negotiating with about 20 fleets to take part in testing of five anti-lock brake systems over the next two years.

In all, 200 tractors will be involved in three metropolitan areas. William Leasure, chief of heavy vehicle research for the National Highway Traffic Safety Administration, said the testing will take place in Chicago, Detroit and one other city yet to be decided. While Denver has been mentioned as a possibility, there are indications that Seattle may be the third site.Reactions to the testing program from both fleets and manufacturers have been extremely positive. The federal involvement is credited with speeding development of anti-lock technology while keeping participation voluntary.

Under the program, the safety administration will pay for the anti-lock systems as well as the instrumentation and data collection necessary for the tests. The agency also will pay some portion of the cost of engineering the systems onto the trucks themselves, although most of the cost will be borne by the manufacturers.

For some truck makers, the program may be providing the extra push needed to get involved with anti-lock manufacturers in a market that is bound to grow rapidly, with or without regulation, in coming years.

Mr. Leasure said that it may be impossible to field all the combinations of anti-lock systems with trucks made by the seven major truck manufacturers that have expressed varying degrees of interest in the project. But at the very least, the tests will assure a proliferation of anti-lock offerings that might otherwise take many years more.

The anti-lock makers known to be participating are Bendix Heavy Vehicle Systems of Elyria, Ohio; Robert Bosch Corp. Automotive Group of Broadview, Ill.; Midland Heavy Duty Systems of Owosso, Mich.; Rockwell International Corp. Automotive Operations of Troy, Mich.; and WABCO Automotive Products Group of Southfield, Mich.