It's a current-production part, so you're not hunting for NOS or surplus — it's a standard catalog line for new builds and replacements alike.
What the D-curve means on this breaker
The D-curve trips between 10× and 20× In (800 A to 1600 A instantaneous). That's sized for loads with high inrush — think motor starters, transformer primaries, or welding equipment where a B- or C-curve would nuisance-trip on the magnetizing surge. For a 80 A frame, that means it holds through the 5–10 second cold-start draw of a 30–40 kW motor before clearing a hard fault.