I took apart my transmission in order to replace leaking gaskets. When I took the transmission out, I forgot to put the 4x in neutral so now that it is put back together and running, when it is in park, it makes a loud grinding noise. I asked an auto instructor at school what I did wrong and was told that I have to find neutral for my transmission and I have no idea how to do it. My truck has been down almost two months trying to get it back running and this is the last part. I need help! TIA!