why did this plug fall out of my 97 firebirds 5 speed?

[JeffP1167]

This plug was there prior to the vibration issue I have now. There is now a hole on the back of my place where the shifter bolts down. I have never seen this plug just fall out,.

What size of plug originally went there?

 

[Twin_Turbo]

do you mean the freeze type plug on the rear or sort of like a drain plug? If you mean the freeze type plug on the rear of the shifter pedestal, it's removed to be able to remove the shifter linkage.

this

 

[JeffP1167]

Yesthe freeze plug on the back of the shifter pedastal.