i had the mancini bushings, they pushed in by hand. that was the first turnoff. the sleeve was about as thick as a piece of emt conduit, the aluminum had no shoulder to lock the spring in place. the springs could slide back and forth in between the spring hanger. dont bother with there aluminum shackle bushings. they are made for a3/8 bolt to go through like those old shackles with a million holes in them. they arent big enough for the shoulder on the stock shackle. i still have the set sitting in my basement. they told me i could have a refund if i paid shipping back to them.
check out the afco front eye bushings, dirt cheap and hard as a rock. they are delrin or nylon i forget.