Stock rear brake distribution block -- also vent for axle?

Also depends on what axle you have.What year ? 7 1/4,8 1/4, 8 3/4 ?
The 7 1/4 and 8 1/4 have vents on the housing and has a solid bolt.Again depending on the year. I installed a 7 1/4 that was a 1974 and it had a vent in the housing.