What is different on a 450 vs a 250? (7.3L) Do they have a Dana 80 rear end? Are the automatics the same tranny? Does it have a bigger tranny cooler? Bigger radiator? Going to look at a 2001 model crew cab with a flat bed, 150,000 miles (engine replaced at 70,000 miles).

 

Same engine, same transmission, same coolers. 450+ trucks have PTOs transfer cases in some cases. 450s have Dana 110 axles I THINK they are larger then 350 dually axles. They have 19.5 inch wheels so the tires are bigger, brakes are bigger, front axles are beefer, and the frame is beefed up. Pretty much all your suspension is BIGGER. I would be worried about how it was used and maintained if it has already been through an engine.