What I am wondering though is how rest of the tractor held up with an engine putting out around double the hp of the original.  I know Kinze made himself famous doing that with 5020s but those had the weight and the drivetrain to spare.  JD eventually caught up to what he was doing with the 6030.   I had a relative do the same thing.  He put a 6V71 into a year old Wagner TR9 that orignally had 160 hp.  You know what, he had to reengineered the rest of the the tractor by adding oil coolers for the tranny and axles.