The only way to really Know for sure,
Is to Soak the 2 nuts in the circles with your favorite rust busting solution.
Then take those 2 nuts off (And hope you don't break the studs)
(Stop if you think you are going to break the studs.)
Even if it looks like it would be in the open position ,
PO may have beat on the weight and spun it on the shaft.
Then you will know for sure.
If it is stuck open just leave it.
I have always used brass nuts on exhaust manifold studs and Anti-seize.
Better results for removal later. JMO hope this helps.
Brass nuts:
https://www.ebay.com/i/382885444081?...cc4c756fdb1338
Anti seize:
https://www.ebay.com/i/264646878276?...3c86fb2fc062f5
.