My 1957 GMC 600 wrecker has a NP541OD. And it came from the factory with 232HP. And that was more than the 671 Diesel put out. I had a NP 541 in the 550 GMC I drove 60 years ago. It had the close ratio 4th and 5th. The shift pattern was 4th low axle, 5th low axle, 4th high axle and then 5th high axle. We called that setup a working 5th. And I could run away from just about anyone in those days.
