That's the part. If it has a regular bolt in it, it may have been apart before. The original part was wedge shaped, with the threaded part at the thin end. It's referred to as a "lock bolt" in the manual. The new bushing kit should have a replacement wedge/lock bolt in it.
You're right about it being tight to get in there, but it can be done. It's much easier with the bed off the truck, which I take that you've already have done that.
