shudder-torque converter?

[MxerChris]

one of the guys here at work has a truck (2000 auto 4wd) that pulls heavy loads 24k gvw, he has noticed a shudder on accelaration when empty sorta like a u-joint but its not a u-joint, he is thinking more along the lines of the tc, when its loaded he says its not noticable? any suggestions, thanks Chris... ... ... ... ...

 

[Bill Kondolay]

Chris,



At what rpms are this happening at? Bad injeectors can cause this symptoms, oil,when was the last time the oil was changed and what type did he put in?