Oooh, I remember seeing that piece when I put on the crash bars. Crap. I can just use a washer of appropriate width, can't I?
That's what I did. I was breaking about one motor mount bolt a year, always at inopportune times, until I shimmed it with a washer. Went to the hardware store and looked through the drawer of appropriately sized washers and found there were about three variations in thickness that my eye could discern. Grabbed a few of each so I'd have options.
Another important thing, use the proper torque on these bolts. I was doing it by "tight enough" feel. When I finally got a torque wrench I was surprised at how much less effort I used. I was probably stressing the bolts when I did it by feel.