Question on installing polyurethane leaf spring bushings

[E.D.75GMC]

I purchased the shackle bushing kit from Energy suspension, and I've gotten to the stage where it's time to install a new bushing. Now, it says in the instructions that you have to remove the old metal sleeve that goes between the bushing and the leaf spring shackle eye. I have no easy way or pneumatic tools to remove this sleeve and my question is; is it a bad thing to leave this sleeve in? The new bushings fit inside it well and the sleeves are in good condition and clean inside.