1) File a small slot parallel to the lollipop face. This will be to hold the lollipop with a screw driver and orientate the lollipop for proper placement. If the lollipop has different facing use a sharpie and mark half if the slot to indicate forward or reaar facing.
2) Tie a piece of small foam to a string.
3) Insert the foam from the exterior of thr 3/8 hole and use a vacuum cleaner at the open end of the exhaust pipe to suck the foam.
4) Remove the foam and tie the string to the lollipop thread rod.
5) Use a flex grabber and grab the lollipop.
6) Insert the lollipop with the grabber and use the string as a guide to the 3/8 hole.
7) Work your patience to get the threaded portion to exit out the 3/8 hole.
With the grabber still in place, if need be, remove th string, insert the nut and finger tighten. Remove the grabber if need be, align the sharpie marked to the correct orientation. Use a small screw driver inserted in the slot and tighten the nut. Verify orientation.
Thats how I would approach that problem.