pulled the nut off to put on license plate bracket, was very easy to take off. noticed that nut and stud are both stripped.

what are my options to fix this?

I fixed mine with a split collar...

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1281894831



Got it at OSH

I got wondering why these bolts would strip -- other than people tightening them way too tight. So I went out and looked at mine on my disassembled frame. One nut spun off easily and the threads were big and crisp.  It's an M10x1.5 after all, not something wimpy. The other nut had to be persuaded off with a wrench, though. It was never finger loose. Hmmmm.

The threads on the mounting rod looked a little ragged and I tried putting the other nut on it just to see what would happen. It wouldn't spin on like it did on the other side. Okay. Then I tried the nut from the difficult side on the shaft of the easy side. It was stubborn there, too. Okay, so both the shaft and nut were ragged, and it was probably the nut that had messed up the threads on the shaft.

I got out the metric tap and die set to clean up the nut. But since it's an acorn nut, the tap bottomed out before it could chase all the threads. However, the semi-cleaned up nut (pictured below) would spin easily onto the shaft until it hit the ragged threads.



I don't know whether the nut was messed up from the factory/dealer or if the previous owner had managed to bugger it up. Either way, I'll probably replace both acorn nuts. They're scratched up anyway. I'll add them to my stainless steel fastener order. The rest of you might want to check the threads on your acorn nuts.

It's 14mm, top and bottom.

I removed the acorn nuts securing the shocks on my bike, the nuts and the threads on the shoulder bolts and posts looked fine.  They weren't very tight.  Maybe previous owners of some of these bikes messed them up.  I doubt that the acorn nuts are high grade fasteners.