2017 Sierra clunk at take off

Mackenzie Stephenson · March 3

2017 Sierra 6 speed 5.3l 4wd. Has developed a clunk/thud at takeoff. 205k kms. Has a 2.5" rough country level that's been on there for about 90k. It's only from a dead stop. If I hold the brake and rev it a bit in drive and let off I get a similar thud. Not sure if it's the same though. Locked in it a gear and tried to get it to clunk at speed but it won't do it. Torqued the rear ubolts and leaf mounts to spec. All seemed tight, clunk still there. Anything else I should be checking? It had the leaf spring tsb done under warranty, this is definitely not the same noise. Seems like slack in the driveline. Transmission was rebuilt at 155k under warranty after torque converter let go, hoping it's not something in there... Motor mounts, sway bar?

rav3 · March 3

22 minutes ago, Mackenzie Stephenson said:

2017 Sierra 6 speed 5.3l 4wd. Has developed a clunk/thud at takeoff. 205k kms. Has a 2.5" rough country level that's been on there for about 90k. It's only from a dead stop. If I hold the brake and rev it a bit in drive and let off I get a similar thud. Not sure if it's the same though. Locked in it a gear and tried to get it to clunk at speed but it won't do it. Torqued the rear ubolts and leaf mounts to spec. All seemed tight, clunk still there. Anything else I should be checking? It had the leaf spring tsb done under warranty, this is definitely not the same noise. Seems like slack in the driveline. Transmission was rebuilt at 155k under warranty after torque converter let go, hoping it's not something in there... Motor mounts, sway bar?

This what I've read on the internet. It's the lack of grease on the driveshaft splind shaft that goes into the transmission tail shaft. I've seen guys on YouTube drop driveshaft, clean both splines, add grease to splines and the clunk went away.