KYB had more than one type of shock. The most commonly used ones were the Gas-A-Just ones that were painted white.
These were sold through Year One, Classic Industries, PST, Energy Suspension and surely other companies. From what I was told, they are a Digressive
design where most decent shocks are progressive. The following applies to NON adjustable shocks:
Digressive means that during suspension travel, the movement from a static state is harsh but the further the suspension travels, the softer the shock gets.
Yeah...initially firm but softening up as the wheel moves further up or down. This artificially makes stock springs and torsion bars feel firmer than they really are but if you have larger bars and stiffer springs, this makes for a harsh ride.
Progressive means that during short suspension travel, the shocks are soft but as the suspension travels further, the shocks get increasingly firmer. This allows the suspension to soak up minor road imperfections but then tighten up as the suspension moves more.