ok i just put a new 3rd gear syncro sleeve set in it and a new outer mainshaft bearing and after driving about 100 miles the tranny is whining while in gear only. this is a hydro tranny if it helps. any ideas on what this could be?

 

while in 3rd gear only or while in any gear only?
does releasing/engaging the clutch make any difference in the sound?

 

could be one of 2 things... either its because the syncro is brand new or that the backlash set between the gears is out of spec..