Gearbox "Clunk"

Hi All....my previous post on this didn't describe the problem very well, so I will go again:

Had a new heavy duty torque converter installed last week and while the new converter is great, I now have a strange "clunk" from the gearbox which I didn't have before. The "clunk" is different depending on whether I select "D" or "3".....as follows.

in "D" :

Upshifting from 1st to 2nd very noticeable "jerk"
Upshifting from 2nd to 3rd less noticeable "jerk"
Upshifting from 3rd to 4th very smooth
Into overdrive Very smooth

Downshifting from overdrive into 4th very smooth
Downshifting from 4th to 3rd very smooth
Downshifting from 3rd to 2nd and 2nd to 1st very noticeable "jerk" and "clunk"

In "3" :

Upshifting symptoms are the same....however there is no jerk or clunk when downshifting

Anyone any thoughts...why the different behaviour on downshifting when in "3" compared to "D". Am I into the realm of valve bodies and solenoids and how to I diagnose and fix?

Additional info: Gearbox oil changed with Dexron3 when the converter was replaced and level double checked and level ok. Adaptive settings reset on gearbox. Scanned for faults with diagnostics and none showing up. Mileage 133,000 Miles.

Thanks for any input guys.

this symptom is common and the result of more complementary wears in the transfer box -> diffs -> shafts link... i had it too and got rid of it completely only after i replaced both diffs and overhauled the transfer box... the greatest 'lag' in my case was from the rear diff which was completely worn as i was dumb enough to not check it from time to time and the breather got clogged so lost most of the oil and ran it so for who knows how long

first rotate the props by hand.... you dont have to find more than let's say 10 degrees free movement in them... where you get more remove it and see where the bigger play is in the tansfer box or in the diff but imo you have to fix them all to have a 'clean start'... then you can forget about it for the next at least 100k miles... provided you check the oil levels at least once a year

Thanks Sierra....but the cluck only started after I got the new HD Torque converter put in, so could it be that the diffs etc...that you suggest are now showing up as a result of the extra "kick" from the bigger TC?

I'll look into replacing the Diffs anyway.

might be...check the free play in the propshafts to make sure

also with the HD TC you better get a transfer box master rebuild kit and a HD cross pin in it too...then you'll be on the safe side