bad shifter vibration over 4k rpms

[devonkyle77]

shifter bobbles back and forth fast as F over 4k rpms
tranny mount is a brand new nismo, and is installed correctly.
b&m short shifter is secure, and has been on car for years.
motor mounts are oem, but also fairly new (6 months)

what could it be? it is pretty bad, and seems to have just happened overnight.

[OptionZero]

http://www.zilvia.net/f/showthread.php?t=105426&highlight=shifter

[dr.slide]

maybe the bushing on the bottom of the shifter fell off/ broke?

[GreekRPS13]

try your tranny mounts?

[cencal180]

driveshaft..........

[zugoi]

Gas cap cover.......

[smelly240]

Gas cap cover.......

???????^

effoffmsglength

[devonkyle77]

driveshaft? what about it?