I have a 2001 Silverado 4x4. I recently bought a 4l65 for a good deal. I helped pull the trans out of a working truck. Then installed it in my 01. The donor truck was an 05 SS. On start up everything is fine. Once it is in gear you can hear it engage the trans. Then it will free spin like it's in neutral. Checked the trans case it's fine. Any ideas or suggestions would be great. Thanks in advance.
