Trailing Arm Bolts

[COONDOG1]

Ok....so I am in process of rear end and torque tube assembly for a 1934 Ford pickup. As I have picked this project up in a million piece s and never worked on anything this old it has become clear that castle nuts were widely used on these vehicles when original.
Question is about the trailing arms...can standard locknuts or lock washers be used and will they stay tight?? Or do I need to use castle nuts and cotter pins on this??