It may be too late, you already have your new machine home, but chances are you are going to move your machine at some time in the future. You need a vehicle large enough to transport the machine. Pinball machines are roughly 30" wide (facing the backglass), 76" to 80" tall and about 56" deep. Folded with the legs removed they are approximately 30" x 30" x 56".
Before loading the machine in your truck, you should fold down the backbox and remove the legs.
Most pinball machines have bolts that hold the backbox upright. Before you begin folding down the backbox, remove any loose items (balls etc.) from the cabinet, replace the playfield glass and lock the coin door. Many pins less than 15 years old also have an over center latch on the back of the backbox. To get to the bolts, you must remove the backglass and open the backbox door to the solid state (control) boards. At the bottom of the backbox there will be 2 to 4 bolts. Remove them, close the door and replace the backglass, lock it in place and carefully fold the backbox down onto the playfield. I would recommend placing some foam between the playfield glass and the backglass, this will make sure that the backglass stays put and securing the backbox to the cabinet so that it will not bounce up and down. Be careful not to damage the cabinet.
If you have someone else to help (highly recommended) you can each grab one end of the machine and carry it to your vehicle. Once you get the pinball machine to your truck, you can have someone hold the machine up and remove one leg, prop the machine on the tailgate of the truck, remove the other leg, slide the pin partway in and then remove the last two legs. A better way (and one you can do by yourself) is to sit the pin directly behind the trunk, lift the end closest to the truck and slide a sawhorse under it. Remove the two legs and slide the pin on the sawhorse onto tailgate of the truck. Remove the last two legs from the pin, remove the sawhorse from under the pin and slide it into the bed of the truck.
Your other option is to use a two wheel dolly (a refrigerator dolly works best). Put the dolly under the pinball machine with the wheels under the back of the machine. Remove the two back legs of the machine and lower the pin to the dolly. Slide the dolly up against the end of the pinball machine and tilt it up till you touch the bottom of the cabinet. Stop here and strap the pin to the dolly. With the machine secured to the dolly, lift the dolly upright, sitting the machine on its back. Now you can remove the front two legs.
You can leave the pinball machine on the dolly if you are traveling with it and you are ready to go when you reach your destination. In most cases you will remove the pin from the dolly and tip it into your vehicle. Its a good idea to load the plunger end first so that when you slide it off the truck bed onto the ground. With it standing on it's back, you can then slide the dolly in place and strap it down.
Be sure to strap the pinball machine down anytime you travel with it. It may not seem necessary but if you are traveling down the road and something causes a sudden stop, the pinball machine could go flying into the front seat.