I changed my transmission fluid over the weekend to MT-90 (diff was changed to Ensos 75w90 GL-5).

Car shifts great now, but I now hear a weird fluid swishy sound. This sound changes in loudness depending upon RPM and gear. Example, when the clutch pedal is pressed in, the sound goes away. If in neutral or any (odd) number gears it's a faint sound. If in even number gears, it is pretty noticeable and loud.

 

That's weird, but if the only change was fluid, I would recheck the fluid level. If you filled it through the shifter hole, rather than the fill port, then see if all of the shifter parts were properly reinstalled, including the bit of cloth insulation under the shifter boot.

 

I too feel it sounds as though the trans was overfilled. Did you end up finding the cause?