The Firehawk kit goes on any UH-60, it takes a long morning to install (after provisions -like the structural attachments and electrical mods- have been installed). The landing gear is lowered using beefy inserts to create the extra belly clearance.
The tank fills with a retractable hose in less than a minute, the tank empties through a longitudinal drop door that sets the pattern quite accurately, I am told.
With the size and accuracy of the drop, combined with the maneuverability advantage that helos have over airplanes to get right down in the hilly terrain to spot the drop, the guys who fly it say it is the best water bomber they have used.