This might be silly but, when you shift it in 4wd, do you line the shifter indicator right over the 4wdhi, or just shift it all the ways down and not quite over the indicator? I a few times when I first got my 85 K10 I'd slam the shifter quickly into 4wdhi and it would slip out and make bad noises. Then I carefully shifted it and I could feel when I got in right. Maybe its just me