85 views to this post and no one can offer any help?
I don’t have a 3rd gen so I am not familiar with it specifically, but can you give some more details?
Is this a new truck for you or has it just started making this noise?
How many miles?
When was the last time the diff / transfer case fluids were changed?
Any metal shavings in the diff / transfer case fluids? (assuming you changed the fluids)
Is the thud every time you disengage or once and a while?
Any thud engaging 4wd?
I am just kind of thinking here…have you check the engine mounts, tranny mounts, etc., to see if anything is lose or broken?