Why would the engine running and the transmission/gearbox in neutral do anything?
There's no relative motion of the transfer case input shaft. 🙅
If you mean the transfer case is in
neutral, that I understand...
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.