Car shudder while on 3rd to 4th gear

[FIRZ67]

Hi All,My ride is a 320 E90 year 2005. Recently had my problem with i highly suspect it is from the gearbox. Car feels shudder between 3rd to 4th gear and at moderate speed. Normally in between 40-60 kmh.Had my car fully diagnosed with GT1 at my mechanic and they found NO fault code stored. Check details like ATF level,AFM,ICV reading,spark plug and finally mounting for engine and GB but everything is intact.Need oppinion from u guys what could be the culprit or my gearbox life has come to its end.Any of members here that had the GB problems without any error code or indicator?Since my mechanic said that if the gearbox is about to fail,the indicator such as 'limb home' should have appear on OBC or from the GT1 diagnosis.Thanks.

 

[Herbert]

Check your gear box mounting.

 

[FIRZ67]

Check it already but the mechanic said the mounting are OK.