Landing gear/ Gear box replacement

The issue is whether the screws will back drive without the resistance of the motor. I would say probably not, but unknown and I would not risk it.

I also would not hitch up to the truck. I would support the trailer with jack stands or blocks. You don't really want to work in there with the truck in your way, do you?

Your jacks are screw jacks so you could replace the motor while in the support position without support of the 5er being hooked to the TV.

Thanks for the help and suggestions. I did put jackstands under frame just in case, but did not need them.
I did have to use the manual turning rod to align with the spline on the motor shaft. All in all it was easy switch.
I don't understand why the factory used a plastic case instead of the aluminum one I replaced it with, I guess it has to do with cost.