04 Z71 Weird Shift

[04z71steve]

i have an o4 z71 silverado extended cab and sometimes i'll get in my truck and it shifts like a idy 500 racecar, the shift is perfect and barely felt, but there are times when i'll turn the corner or be comin down the street and the truck will shift hard and if the windows are open you can here a pecular tap underneath, when i bought the truck they had to tighten my transfer case, but my dealer is a bank robber and i'd like your advice before i go in and have him check it out your help or even suggestions would be greatly appreciated!!! thanks

[Draenor]

Maybe a broken tranny mount. You could try crawling up underneath and try to wiggle the transmission. Next try to rotate the drive shaft, if there is excessive play , you could have a broken u-joint. What exactly did the dealer tighten on the Tcase.

[04z71steve]

i'm gonna try both of those in the morning i tried just reachin under but will it be noticably loose or will i have to give it a good shake? i was told the whole transfer case itself was loose and they tightned it up, but i was so excited about getting my truck that day i didnt really pay attentnion all i knew was that it was fixed and it was time to take her for a cuise! thanks for the advice i'll let ya know if it works !

[04z71steve]

so i spent all day yesturday under my truck, searchin for a loose mount, playin with my drive shaft lookin around the transfer case, and i came up completely empty handed, i actually left the underside of my truck with a smile on, not one drip of oil anywhere! everythings nicely lubed and shes lookin good, my only other thought is that it might be the plugs, i heard that it could be because the truck has a short misfire when its shifting but then that still doesnt explain the tap underneath the truck, i just put some 93 oct. in here and shes runnin great the shift seems to be better, and theres no tap really, so i'll keep knocking on wood!