I had a 1970 GMC 7500 Dump Truck with 44,000 rears (Tandem) and 16,000 front axle, 6V-53T, 5 X 4 (20 speed) transmission(s), (A five speed box on the bell housing, and a 4 speed splitter in the drive line). Only had a 12 ft box w/ this goofy two ram setup...double framed from end to end. It was an ex-Wyoming State DOT plow truck. Tough as nails.
Used it as a truck to spread on mountain dirt roads in Colorado. (Berthoud to Ft. Collins )
Talk about loud. It was an ear splitter!
Power? Guess that depends on your definition. Maybe 225HP. Had to wind the Crap out of it to get up a mountain road. (This was in Colorado).
Those old 6v53's were a tough motor. The only thing that would kill them was getting too hot. Then they would crack heads. They Still would run.....Also had to keep the injector rack set right. I had that little "pick" to set the injectors. Still do. Still have the Detriot Service manuals as well...maybe I'll find a project someday. (If you ever get one and need tuneup specs..)
They sell for scrap prices any more out there. So you should get a good deal unless for some reason you have to have a Detriot.