Bad day here - hope someone can assist in next step. Trying to replace starter - having no progress in removing the top bolt. Looking to make sure I have the right bolt. The bolt that is stuck/frozen also serves as the ground post - can anyone confirm? I believe the nut is a 15mm, seems to be frozen. Looking to verify that this is the top bolt for the starter.

Thanks for the view.

 

make sure you are undoing the correct bolt.
Some people mistake it for the motor mount bolt.

Both starter bolts are 15mm.

The upper starter bolt has 2 ground wires attached to the bolt, that need to be removed with a 13mm deep socket first (1/4" drive is easier).