You say you installed a Mustang II front end on the truck? The company that supplied the Mustang II didn’t give you instructions on how to install the front end? I noticed you didn’t box your frame from the front to the cab. The one I installed told me to box my frame. I would have thought they would have told whether or not to take out the cross member knowing you were changing the motor and trans. I went on line and got instructions on installing my front end from the company I got the front end from. I’d would go back to that company I purchased the front end from and ask them for their recommendation. I’m sure they have dealt with this before.