SPEEA has said it's disappointing the offer does not provide defined pensions for new employees. They would, instead, have a 401(k) retirement plan.
However, the union says accepting the company's last offer would lock in "considerable improvements" achieved since the company's initial offer.
The 7,400 technical workers have already given their union strike authorization.
The 15,500 engineers represented by the same union approved a four-year Boeing contract in ballots tallied Feb. 19.
The engineers and technical employees work on plans for new planes and solve problems that arise on the factory floor.