on the tranny where the vss bolts into. what is that piece the vss bolts into. looks like if you ubolt the vss you can unbolt the another piece below it. what is that. thanks.

 

Not sure what year trans we are talking about....but on most of the newer ones (I'm stuck in the late 80's )that is the speedo holder and gear.

The gear makes contact inside the trans, as the trans is spinning the gear moves sending the motion to to VSS (there is that little drive pin between them) which translates that into electrical "pulses" that go to the speedo PCB....which then translates that into how "fast" the car is moving.