You do not need "pin & sleeve." Hubbell HBL8431C=Heavy Duty, Industrial/Commercial Grade, Straight, 3-Pole 4-Wire Grounding,30A 3 Phase 250V AC, 15-30P
-or- HBL9331=Heavy Duty, Industrial/Commercial Grade, Angled, 2-Pole 3-Wire Grounding, 30A 250V, 6-30P
Or, search Amazon for 250v 30a twist lock.