Based on past promises, Governor Michael S. Dukakis' proposed budget for fiscal year 1984 should increase aid to cities and towns by at least $150 million, without a major increase in taxes.

Dukakis must present the proposed budget for the fiscal year beginning July 1-estimated at about $7 billion-to the Legislature by March 2. Local legislators are now cautiously waiting to see if the governor can stick to his promises.

The largest question is whether he will manage to return at least 40 percent of the growth in state revenue, about $150 million, to localities, doubling last year's allotment. Local legislators stress the importance this extra revenue would have for Cambridge. State Sen, George Bachrach (D.Middlesex and Suffolk) noted that Cambridge is still suffering the effects of Proposition 21/2.

"With that kind of commitment to local aid.: certainly don't see a disaster for Cambridge," he added.

But many observers question how Dukakis will be able to come up with the extra money "What he's saying sounds fantastic, but I'd like to see how it's going to be done. "State Rep Peter Vellucci (D.E. Cambridge) said yesterday. Nevertheless, he said Dukakis "is going to have to make some tough choices, because he's promised not to put any major new taxation on the table."

Financial aid to students will probably be another major aspect of the final budget. Bachrach said Dukakis will offer at least $14 million in general state scholarships from last year's budget. Robert H McLean, undersecretary of administration and finance, said yesterday.

But Bachrach expects the legislature to propose a substantial addition to last year's figure. A late proposal for $45 million in scholarships which never has a chance to reach the floor for a vote last year because the legislative session ended will probably be reintroduced, he added.