Somebody you know must have a 4WD pickup that they think is the greastest pulling truck in the world. A little beer may give them the incentive to hook up and try to move it for you. Depending on the distance, I'm thinking the pony may not live a long life after your adventure.
If you've got the main torn down, I sure wouldn't be using the pony more than a couple of seconds. No cooling means that it's gonna fry in a short time. . With coolant in the engine(s) I've moved my old D2 a few times, but not more than a few yards.
I've used the pony to move the tracks when removing them or walking them back on, but never moved the crawler with it. It goes really, really slow in first gear. But, it would probably do it ok if you put the machine in 1st gear and get your trailer real close. I wouldn't try to drive a long distance though. You are taking a chance on breaking something down in there that requires removing the engine to be able to make the repair.
Years ago I bought a non running 1957 D7-17A, got the pony running and then used that to drive it up onto the lowboy. The lowboy had a winch, but it couldn't get the machine up the ramp without the help of the pony. I guess it was the winch and pony moving the machine, which probably saved the pony drive gear. Though the winch cable was slack most of the time. Some dumb luck was at work.
I pulled my D42T up a 25% grade with a JD 60. 38 HP but didn't need it and 5000 pound and that was plenty.
Arthropod. If you said about 1957 you loaded a D73T in the way you stated, I would respond I watched you. Neither the wrench or the pony wouldn't do the job by itsself but 2 man and a boy got it loaded.
abram - I wouldn't do it. The pony just isn't built to haul the tractor along, and most certainly not up a beaver tail onto a trailer. It's no different than using your car starter to try to do the same.
A 4000 lb electric winch is quite capable of pulling a D2 up onto a trailer, if the tractor rolls O.K. If needed, you can use a snatch block to increase the line pull, and/or reduce the winch load. You haven't stated how far you have to move it? .. and whether you were just going to try and drive it a distance, or trailer it.