This is what I'm talking about @AdamGarrison. This thing worked great when I uploaded it.

This is the crazy crane I originally made for the multiplayer bomber. The end result that this crane became (which is nothing like it) can be found here

This crane is so needlessly complicated and unreliable and required your rear gunner to attach all of the top turrets himself by picking them up off of the ground. I was actually almost ready to post it when I realized how much simpler and easier it could be.

LandingGear - Jackstand bracers. You're going to need these in order to prevent rolling around while you work.

Propulsion - Throttle. Turning is controlled with Yaw, but not in the normal way. The wheels are on 90° rotators. To turn, sometimes it might be best to stop, maybe even activate your jackstands, orient your rotators, then go.

AG1 - Activates big X-Axis pistons at the top (they will usually be obscured from view while you're setting things up). VTOL for red side, Trim for yellow. Pushing down all the way on either side will move that side away from center.

AG2 - Activates second set of X-Axis pistons. These makes it easier to fine tune where your magnets will end up on the X-Axis. These pieces can interfere with each other, so don't bash them. VTOL/red, Trim/yellow

AG3 - Z-Axis pistons (VTOL/red,Trim/Yellow). These can also become Y-Axis and blended controls if you need them to be.

AG4 - This controls the joint and hinge rotators with VTOL/Trim as usual. These rotators work together to make sure your Y-Axis Pistons are always pointing straight down.

Also on AG4, both sides of Y-Axis pistons are controlled with trim. They will always move at the same time. These are the pistons that will reach down and grab your turrets, and place them onto the bomber.

AG5 Activates the rear gunner work station. When it comes time to fly, your most important gunner is the rear gunner. This is the trickiest turret to work with. Good thing your rear gunner will be operating the crane when it's time to play this. He's less likely to get lazy with placement.

AG5 will also activate the main Y-Axis piston for the rear gunner work station (sitting on the Z-Axis before you activated 5).
AG5 also activates the Z-Axis  pistons (sitting on the Y-Axis before you activated 5)

AG6 Activates the left/right fine tuning pistons for this work station, operated with Trim.
AG6 also activates the leveling hinge rotator for this work station. You're going to need it. Operated with VTOL.

AG7 detaches the rear turret. This will be your very last move every time, no matter what configuration you choose, somebody will always have to be at that gun. That's your most trusted gun and Number 1.

AG8 controls the magnets.
Steps:
0.5 Play with the controls! You have to just mess with it to get a feel for it. When you have a good idea for everything, move on to step 1.

1. To start, deactivate AG8. These are your magnets and you don't need them interfering yet.

2. Position the cranes of your choice over the the turret on the ground. You can do this either by driving over it slowly or by using your side-to-side motion pistons on AGs 1 and 2, or a combination of both.

3. Once you are satisfied with your positioning, set your jackstands by hitting LandingGear.

4. Look back at your controls (maybe you should print them out or have them handy on another screen) and use them to manipulate all of the pistons and rotators until you're alk ready to pick up that turret. You'll probably need to activate something, deactivate it, move the controls back to zero before activating the next thing and so on until you're ready to use Pitch on AG4 to lower the magnets.

DON'T WORRY You'll have your gunners giving you big help when I've made everything. It'll be easier, but you'll also be picking up two turrets at a time, so get good at it.

1. Lower those magnets and activate them with 8.

2. Lift the magnets up (note the heavy droop).

3. Raise your jackstands and drive to the practice plane. Position your crane over the plane and do your best to center it. You don't have to be perfect, but the close to center you are, the better.

4. Lower the turret onto the proper magnet on the plane (guns facing out!) Once you're satisfied with the  placement, release the turret. Like I think I said earlier, you can't actually attach it yet. The pilot is going to be the one activating the magnets to attach the turrets. .

5. Once you're ready to move on, work on the rear gun. That one is going to be harder. Be sure to use your rotator to make it level with the magnet for better placement.