Fix your "frozen" locking hub.
I'm gonna guess that your front driveshaft is still turning when you are in 2wd and that you have slightly loose ujoints (worn). With no load on the shaft this is allowing vibrations that are not present when...
If the brake master has been replaced, the booster dowel length needs to be verified. If it's too long, it can continually apply the brakes, heating them up. Over time while parked, this pressure can self relieve.
@Gimme a 60 , i think you are mixing terminology, to bob means to shorten the length of the body n your picture shows what is commonly called a rocker chop :meh:
Commonly when the seal goes bad, the bearing is too. Reusing a already crushed pinion spacer has never been a long term fix for me. IMHO, better to get the third entirely rebuilt.