It was used mostly in DW20 & DW21 scraper tractors.It was used as industrial power use in some smaller drag lines & shovels (not Cat) & also gen. sets & other industrial power needs. There were two different models of the D337 & the early one was just the D337 & the later altogether different engine was the D337F. The D337 was a roots blown engine & the D337F was a turbo engine.Also in the models there was the NA (no blower or turbo) model called D326.
I do have the Operators Manual for:
D337 - 22B1-up, 23B1-up, 24B1-up
D326 - 25B1-up, 26B1-up, 27B1-up
If somebody has questions........no parts manual though😄
Those early D337s weren,t Cat,s best engine that they made. I have rebuilt lots of them years ago & when the D337F came out they were a much better engine.The 37B was the D337F industrial engine & the 38B the F marine engine.