Leo, A bare 6U D4 weighs 10,065 pounds.
for straight blade & hydraulics add 2685 lbs.
If it has a belly pan and rock shields on the bottom rollers add a few hundred more pounds. Now you are up around 13,000 pounds minimum.
I have hauled home three Dead D4s and an HD5 loader. Each was an adventure. One of the first things you have to do is lift the blade. I use a 4ft. farm jack to lift the blade nice and high. This will compress the hydraulic cylinders. Then take a couple short pieces of 3/8" chain with hooks and chain the blade up from the rear of the hyd. cylinder to the "triangle" on the lift arms. Get the blade as high as it will go because this will make it easier to winch up onto a trailer. We hauled mine on a 9-ton tri-axle trailer. It is best to have a trailer with a winch on it to load with. I used a chain come-along to load the HD5 and that was a good work out. Slow but sure. We loaded them on front first but you may have to do it rear first. You will need something to pull the D4 off the trailer when you get it home so keep that in mind. I used a wheel tractor once and a D2 the other times. We hauled mine with an old one ton Ford with a 400 V8. The farthest we hauled was 60 miles. The most important thing is to have good brakes and to leave plenty of space between you and the guy infront of you. Good luck, I wouldn't sell a gift like that either.