ZX75US, ZX70, ZX75: These are model numbers for different Hitachi excavators.
AP2D36LV3RS6-890-3, AP2D36: These are likely specifications for the hydraulic pump used in the excavators. Specifically, they refer to a model of pump manufactured by the Japanese company Komatsu, which is commonly used in Hitachi excavators.
The AP2D36LV3RS6-890-3 is a specific variant of the AP2D36 pump, with the following specifications:
Displacement: 35.7 cc/rev
Maximum pressure: 300 bar
Maximum speed: 2900 rpm
The AP2D36 is a slightly different variant of the same pump, with the following specifications:
Displacement: 35.7 cc/rev
Maximum pressure: 300 bar
Maximum speed: 3000 rpm
I hope this information helps!