another tranny question

I've read a lot of posts concerning the trannies but couldn't find one that matched my problem so here go's. I've got a 99 LS SWB with the 5.3L vortec. Every time I pull up to a stop sign, just before the truck stops, there is a lound "clunk". If it doesn't clunk before the truck stops then as soon as I let my foot off of the brake it will. I've read a couple of posts that refered to TSB's for a "speacial grease" and one for a nickel plated yoke. Are either of these for me? Other than that the truck is solid, lots of power, clean and tight.

Sounds like the yoke. My 99 does the same thing. When you are stopping, the weight is transferred to the front end, just as you stop, it transfers back, dipping the rear end, and the yoke slides on the output shaft spline, CLUNK! Had a nickel yoke put in under warranty, 2 years ago. The same problem came back about 6 months ago. If it is a 4x4, I heard that if you change to the blue transfer case fluid, it will fix the noise.
It is Autotrac II Fluid (Blue Stuff), gm part number 12378508

called the dealer and they said that the nickle plated yoke on the TSB was just for the Ext cab 4WD models. I guess I should have specified that mine is a Reg cab 2WD model.