Did you get the 4.9 Final Drive and shaft from King? Was it recent or a while ago. I have a King final drive and it had to be modified by King. The newer units (sold but not made by King) fit better.

I had the 5 to 4 issues, could get into 5 but not back out. Turned out to be an indent ball missing that wouldn't release out of 5th and push into 4th.