99 Z-71 drive line clunk question

I've read all the post for the past couple of months concerning the drive line clunk on chev. z-71 pickups. I was wondering if anyone had investigated the possibility of axle wrap causing this? My truck
developed this clunk after I took it in to the shop for a front chunk seal replacement. I ask while it was on the rack to change the tail shaft seal on the tranny,and the next day is when mine started. It might have been just a coencidence and it was due,but mine had absolutely zero clunk to it before the work. I carried it back and the tech packed the yoke and it quit for about six weeks. Started back and I made them put a new yoke on it,even though I saw absoluty nothing wrong with old one. My truck is not an ext. cab so I didn't get the nickle plated yoke,dealer said that the nickle plated yoke was for ext. cab vehicles,so mine was a gm. factory stock yoke, anyway it stopped it for about a week and it has started back again. The weather has been so bad here I havent gotten under to look at every thing,but it feels like it could be some axle wrap.I can re create the clunk at any light stop or traffic sign with the touch of the brake pedal, and relieve it in an inch or two of rolling. Thats why I ask if the rear calipers and/or front calipers could be dragging a tad bit and make it feel like drive line clunk. It doesn't seem right that the rigid frame would flex that much to make the yoke hang on the tail shaft. Its just a thought and if anyone has any ideas,I'm open for suggestions. Besides,where is all that grease going when we pack the yokes? None of mine is on the floor,or underneath the cab.
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Mine was also making a "clunking" noise, turned out to be leaf springs.

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Thanks for the reply.I am going to check it out.I tend to believe there is more to it than just a yoke. Packing the yoke just keeps it from moving any,and it would make sense that something else has given up to let it travel forward like that. Just witch hunting,it aint over till its over.
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Just a quicky,I checked the u-bolts on the axle hangers and the nuts were loose and I saw evidence of movement, (sliding about 1/8" on spring pads). Drove it to lumber yard and vast improvment,cant re-create the noise like I could, but I'm still not satisified that is all it was.... to easy.
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my wife had that problem with her '99 tahoe. it was 'sticky' transfer case lube. chevy issued a TSB addressing this problem...might want to check it out.
http://www.alldata.com/recalls/index.html

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