Boom. Found em. Distorted thread locknut.
https://en.m.wikipedia.org/wiki/Dist...thread_locknut
And I also found the Fastenal brand top lock nut.
I will get one of these and replace the nylock nut. I've used these before now that I'm setting them... And as for putting the bolt in the other way that is out of the question as the adapter plates are right up next to the block and these bolts come from the backside so can't switch them like that. I should be able to clearance a small amount of that clamshell top plate and use the top lock nut. Thanks guys, I will report back here and on my build thread when I get this completed.
