The metal inserts for the upper and lower mounts clean up nicely after heating them with a propane torch and wire brushing off the charred rubber residue, with only a few marks from the hacksaw used to get rid of the bulk rubber. Then I used a utility knife to cut it down close to the metal, then hit it with the torch to char the remaining rubber that was attached. After cooling, I used a file to round down the edges so that pressing them into the new bushings wouldn't cut the rubber.
Unfortunately (and I found this out after unsuccessfully trying over and over), the upper OEM metal insert on the has a much larger OD (3/4") than the rubber bushing's ID (7/16") supplied with the Hijackers shocks. Forcing it in with the vise only served to split the bushing. The Hijacker's bottom rubber mount is just the right size for the OEM lower insert. It fitted right in by hand with a little silicone lube spray...the rubber went into the eye first, then the insert went in.
So, I was left to find new rubber bushings for the top that would fit both the Hijacker's ID as well as the OEM insert's OD. I looked online at Energy Suspension and saw a few possibilities, but didn't want to go to urethane unless I had to.
I searched the auto parts store's HELP! racks, but they are very limited and didn't have the right size. I did notice that the lower bushing would work for the upper mount as well, so I called Gabriel's support line. However, they don't have a separate part number for that bushing. Dead end there.
Back to Energy Suspension, their 9.8140 shock bushing looks to be the closest fit, so I've ordered two sets (they come in pairs) to do all four shock mounts. Hopefully, the ride won't be too harsh...but anything will be an improvement over the rocking chair ride I have now. Should get them in a few days.
We're getting there....