It's not just the power, did you ever see that frame twist test they did between a Dodge and a Ford dually? The Dodge with it's wheelbase and frame/suspension package is unbeatable in the stability department. Best dually EVER! So I guess my answer to the OP would be, if you have a Dodge dually? Pretty much haul whatever you want.

Thanks guys.

He is going to rent a u-haul box truck to pull it with since he has no truck.

I'll make sure he gets a good size box.

Might be a bit late to the party but here is my experiences w/a U-Haul auto transport trailer and C bodies. First of all they will not rent to you if you tell them you are putting a 1969-1978 C body on one. I usually tell them I'd loading a 1985 Dippy/5th Ave/Ply.Grand Fury and they are happy.

They fit but just barely. C's will have about 4 or 5 inches of trailer deck left behind the rear tires with the front tires all the way forward against the stop block. Massive overhang front and rear and really, really heavy tongue weight. 3/4 ton truck did ok, no sway but a 1/2 ton might want to keep the speed down or rent/buy load levelers to help. As to the overhang on the front, didn't cause any issues with the tailgate or bed corners in turns but I was watching and tried not to do any minimum radius turns. Aft overhang...well you could just about park a subcompact car under it if you wanted. It would be very ugly (for both of you) if someone was tailgating you and didn't get stopped in time. Also keep a look out the opposite side mirror to see where the tail end of the car is going when you make a turn to keep from clipping something, pole, sign, person, gas pump, with the outside rear corner of the car.

I have carried two Imperials on U-Haul trailers.......not fun and would not recommend for long distance. The extra 3 inches of wheel base uses up just about all the deck space, had to deflate the front tires some to get the car far enough forward to get something attached to the rear tie down rings. The additional weight of the Imperial is very noticeable and maxes out the front axle/springs/tires.

have it shipped, renting a box truck & trailer to haul it is not going to be cost effective with rental fees, ~$.59 a mile and fuel (round trip or one-way?)

unless he's moving a bunch of other stuff with it

Here is a pic of my Challenger on the U-Haul trailer I used. The car was definitely not too wide for the trailer, and it was an approved combo by U-Haul. I think a C-body would be OK - just hanging off the back a little.

It will fit ... Ive hauled several 70/71 C bodies on a U Haul trailer. They wont let you haul a C on there so tell them a 1970 Dodge dart with a slant 6.
The furthest I hauled was from Jersey to Missouri empty and back loaded..