i seem to be having some trouble replacing my vehicle speed sensor. i have it in up to the O ring but can't seem to get the O ring to seat in the tranny. feel like i am hitting somthing with the bottom of the sensor. any ideas??

 

check that your new is same as your old, if so, then try to rotate it left and right and try to slide it in, There is a gear behind there, and you have to slide in. Oil the sensor O ring a bit