Maybe these photos will help?
Why the chain? Do you have a lock on the J-bolt?
The chain is not on the original assemblies. It was added as a “belt and suspenders” precaution to avoid loosing the lock on the J-bolt. The chain was a copy cat application from a long ago contributor, I think here on the SB. Locks were an accessory available from the dealer. There are several different versions. They occasionally show up at the e auction site.
Edit: The chain attached to the lock keeps the lock from being lost in the grass/dirt during the frustration and hassle during a tire change process. I understand that a big reason parts of these spare tire carriers are so few now is because many of them were launched across the country side in frustration.
