Here is a link to the nebraska test for a 1955 7U
digitalcommons.unl.edu/tractormuseumlit/1042/

Max corrected HP 52 drawbar and 62 belt hp

Caterpillar advertized Drawbar HP is 48

I have my Cat factory rack setting book here I used at the dealer and the 6U up to 7049 and the 7U up to 15661 lists the HP as 51 at 1400 RPMs full load.To get the correct HP of tractors and other specs. you really need the serial number of a tractor as the specs change with different production of them. I have no specs of D4s any higher than the ones I gave as my books aren,t any later.Wish I had some later books but don,t. Where you go crazy with settings and HP is with the industrial engines as there are so many settings and HP. Take that same D4 style engine (D315) the ind. settings in the book run from 33 1/2 HP to a max of 73 1/2 HP with fan. Rebuilding engines and dyno. testing them at the dealer you had to get all the specs correct for the application it was used for and most the Ind. engines had the info. (specs.) on a plate on the engine with the SN.