New shackle on old Yale PKPT padlock

[candado3]

I picked up this old Yale PKPT padlock recently and was surprised by what I found.
It looks like a new taller shackle was made and attached to the lock.
The new shackle is made from steel and there is a small gap where it is attached to the old shackle assembly. (see photo with a shim placed in the gap) There are what appear to be file marks on this new shackle.
I don’t know how the new shackle is attached. I hesitate to try to remove the new shackle as I am afraid that it may cause permanent damage.

Anyone have any thoughts on this or why anyone would go to the trouble of doing this?

I have attached photos to try to show this.
Note: The collet ( is that the correct name for it) that houses the shackle on the other side has been loosened