Well, that's one of the more patience-inducing 1st world problems I've gotten past on the XJ. That adapter fastener (#60 Torx), the nearness to the frame and the slight downward angle make for rather difficult access. My adapter is situated such that the filter attaches on the back side parallel to the ground. I had a #60 Torx L-Key wrench but the angle of the free end was all wrong for turning it. So, I cheated and watched a video of a guy who punched a #60 Torx bit out of a 1/2" drive socket, used the bit with a 9/16" box end wrench (14 mm), coupled to another longer wrench, and broke the fastener free. Worked like a charm but I will say it took quite a bit of umpf to break free. I still have my knuckles. The old o-ring was totally compressed and age-hardened to a plastic state. The new o-ring kit was around $3.00. Note: Use plenty of Vaseline or Teflon grease on the internal bolt o-rings to allow it to turn easily when replacing the adapter back onto the block. For me that was a one-hand operation to get a few threads started so you want that bolt to turn easily.

 

Could have removed the motor mount bolt and jacked the motor up on that side. Though I never needed to.