sunroof tension bolt and nut - stripped

Now to the next problem. The same car ('88 260e) has a problem with the tension bolt on the sunroof motor. I guess I tried to tighten the nut too much, now it's stripped and so is the bolt. I can't enjoy the sunroof with all this great Florida weather.

I've added washers hoping to use the "good" threaded part of the bolt... but the nut is stripped. I've searched all over central florida for a new nut... but can't find one.

Any ideas? Any sources for nuts and bolts for sunroof motors??

Thanks!!