OEM vacuum booster
Hydroboost with 40 mm master cylinder
Hydromax with 2" master cylinder
Hydromax manual link
Brake pressure from Hydromax
2" Hydromax master with reservoir removed. Built like a "P30" master
Booster poppet valves
Hydromax master at assembled length. Volume ratio between sections 1 to 1
Hydromax rod does come out and a few styles are available or make what you want. New grommets are available.
Hydromax is different than Hydroboost in that the hydraulic flow path can have no restriction on the outlet, not a power beyond deal. Need a separate engine driven pump on the GMC or some kind of dual section pump. Relatively huge volume from the large master should satisfy all disk brakes with big pressure. Backup electric pump on primary flow failure.