HELP! '97 Z-71 Transmission Clunk

I recently purchased a 1997 GMC Sierra Z-71 X-Cab with 76K miles. It has run fine but recently developed a slight "clunk" when shifting from 2nd to 3rd. Does anyone have a clue what this may be?

Thanks,

Barry

My 97 Z71 has a clunk. I bought it with 123K so I am sure it has been doing it for some time…. I think that I have read that it is normal. I imagine that means if it isn’t extremely loud. I noticed riding in a friends 2004 Z71 that his was doing the same between 2&3. It was quieter than mine but I could still hear it.
Did some one post that there is a special transfer case fluid that helps with this?

welcome to the wonderful world of the mid-90's early-00's model 4L60E!!! Most all of em do it.

Yep mine has the good ol clunk too. on mine its not so much the sound, the sound is coming from the driveshaft and U-joints which can develop slack over time, when you accelerate and the slack is picked up CLUNK. but i can definatly feel a heavy shift, maybe more of a thump since i dont really hear much noise from the tranny. i dont see it as a problem or something im gonna bother tryin to fix, the truck isnt even close to new so what can you expect.

If this only happens after you go about 45 and if you
can turn the truck off for a sec. and the prob. goes
away, then it is probably a common valve guide prob.
in the tranny which can be fixed with a kit if it's not
too late or you can wait and replace your transmission
and torque converter as I did in my 97 GMC.
Good Luck

Thanks for the info. I sold my '94 Z-71 with 194K and no tranny problems. Was that a 700R4?
My clunk isn't big enough to be felt much - it sounds like more of a higher-pitched rattle, as if some piece of metal is loose and rattles a bit when the shift occurs.
I have been careful to test it under steady, moderate accleration (it clunks), rather than pushing on, and letting off, the gas.

Having ditched a high mileage truck with potentially expensive engine and tranny problems soon to occur, I spent at the top of my limit to get a low mileage truck. I don't want to have to do tranny work!!!

Barry