I own 5511, it's very original but I've noticed a couple of things I think have been changed. Let me know if I'm correct.
The airbox screws are screwdriver type not 8 head hex bolts. They are easier to start so that's probably why.
The grab handle has an 8 head bolt but it appears almost recessed into the handle, I can turn it just barely. I'm assuming it's been overtightened severly or maybe it's missing a washer.
It had lowering blocks and one rear axle retainer bolt was swapped for an allen head. I found a later 8 head bolt to use but it's of course not correct.
Is there any new information about the early 8 head bolts? I guess also, is 5511 new enough to start seeing a mix of the different head shapes?
Thanks.