Is the nut on the back off already? Nothing threaded I know of just the nut on the back. When you go to reinstall tq the nut instead of the bolt.

 

You should be able to drill it, in my Parts Catalog it looks like there is a bushing around the bolt, so if you hit that, you've drilled enough, maybe take a chisel and whack the head from there. Probably want the bike on a lift, or someone holding it. I was going to use button head bolts, but much prefer the old six side hex head, easy peasy.

John

 

Lower mount bolt part # 4354 is listed as:
SCREW, 1/2-20x2 1/2", Torx button head, shouldered
I remember about 6 or 7 years ago, when I tried to get a socket head bolt to replace the upper and lower shock bolts, it wasn't a problem getting a replacement for the top. Finding one with the proper thread pitch and shoulder for the bottom mount proved fruitless. I went with the stock button head. I guess if the thread pitch wasn't a concern, you could find something besides the stock button head.

 

I was going to replace my stock one with an SS allen buttonhead, but could not find one that was not completely threaded. The stock one has what looks like a uniquely long shoulder, so I just put the stock one back on. I has to go through the shock eye bushing and swingarm before the threads start. Not sure if this is critical, but I just left well enough alone.

John

 

Did you try using a wrench on the nut in back first? I had an issue with something similar, and it's easier to get it off from the nut in back. it will take the torque better then the torx will.

 

Had some time today and got it off. I used a grinder with a metal cutting wheel and cut off the head of the bolt. That allowed me to slide it towards the backside and loosen the nut. Once the nut was off I lifted it a little and slid the bolt out. Upper belt guard is off. Now all I have to do is get a replacement bolt and I'll be back on the road.