Sept 16 (Reuters) - Striking workers at Boeing Defense

will vote on Friday on a four-year contract proposed by their

union in an effort to end a six-week strike, the International

Association of Machinists and Aerospace Workers (IAM) announced

Tuesday.

The IAM's proposed offer builds on the company's proposal

with a larger ratification bonus, better retirement plan

contributions and better wage increases for workers at the

hourly wage ceiling.

The roughly 3,200 members of IAM District 837 voted 57% to

reject Boeing's ( BA ) last offer on September 12.

Boeing Defense did not immediately respond to a request for

comment.