I'm trying to remember..... On the 88 ITD I had, I replaced the pivot bolt with a 5/16 and put nylocs on it. As I remember, on the original, one end was rectangular and fit in a "slot". That end had rounded over and wouldn't stay tight. I think I resorted to double nylocs or something like that to keep it from working loose.

89 3L V6 5spd SWB, Aisin Manual Hubs, 2 (suspension) seater Raider in Wheeler, OR