Lock Washer Swing Arm

[Hooter123]

Have been rebuilding 1981 xs400 that was gifted to me torn apart. Is it important that this lock washer is same part #, or do I not need to grab one for off EBay

 

[CaptChrome]

If you buy the correct part number, you are pretty certain it will fit and work correctly. If you don't, it might work, but also might not. For 10 bucks, why take the chance?