How many seabees were in the movie the green berets?

It is interesting you mention this as actor John Wayne starred in both Green Berets and The Fighting Seabees- about Navy Construction Battalion men. I do not recall any Seabees in Green berets- essentialy ground-combat with big mouth Wayne. The character Wayne played in Fighting Seabees was based on a Naval Engineering officer who was a real man. When in Dress tans- the actor did somewhat resemble this man and not utility-hero-man Wayne.

When Col. Kirby's(John Wayne) A Team arrives at thier forward base, he is able to eventually get a Seabee detachment to come in and clear trees and some other work. The camp later gets overrun by the enemy and the Seabees assist in defense. The Seabee C.O. is wounded while defending himself from atop a Cat dozer .Additionally, according to the dozer operator, clearing trees is "Like mowin' the lawn".