[Rev]

Doesn't the new idler arm have a sleeve built into it that should go onto the existing fixture bolted to the unibody? That fixture looks kind of like a spindle that the sleeve fits over?

I haven't done this in 5 years or so, but that's how I seem to remember it. If that's correct, I would just use some WD-40 and maybe Vise Grips to rotate the old sleeve until it loosens on the spindle fixture until you can get it off. Sounds like it's just stuck to me. That's assuming that the the new idler arm has the new sleeve built in as I remember.

If all that seems correct, then after you get the old sleeve off just clean off the spindle with a wire brush, solvent, maybe emery paper and slide the new part on and bolt it up. At least, that's how I remeber it when I did mine some time ago.

Rev