for everybody that is using offset shackles

Yes. The old perches are generally canned. The accepted and easiest method to remove them destroys them. You cut them down the center length wise and break each individual piece off. But be forewarned. If you get the MP replacements, the damn locating hole for the leaf spring pin IS THE WRONG SIZE! It's too big. I always used Competition Engineering, but I am sure Mancini has some too. They are not expensive.