Technical Vacuum question Ford flathead V8

I have a question to you flatheadguys. Why did they move the vacuumline to the distributor when they change from the helmet to the crab? is it a vacuumdifference in the intakemanifold or? Thanks in advance Anders W

 

Manifold vacuum is plumbed to the retard brake on both distributors; directly on the helmet and indirectly on the crab through an internal passage.

 

Thank you V8 Bob but I mean why they change the vacuumline on the manifold? sorry for not being correct in my question. Anders W

 

Some pictures of the difference in plumbing will help answer your questions.