T56 chatter after fluid change
 

i swapped out the Redline D4 since i heard it's bad for our synchros, dropped in regular Shell ATF (dex III/mercon)

on first drive i heard a rattling sound. i thought something might have fell in since i filled from the shifter. i also adjusted my B&M ripper shifter back with the spacers so not sure if it's that.

when the car is idling i can hear it. bending down outside the car, it sounds like it's coming from the trans, like something metal is bouncing around in there.

is this chatter? what fluid should i swap in there? thanks