Just looked at the final drive section in the linked manual, as this section was revised a few times, but it appears to be incomplete, some of the sections which were revised are simply omitted.
Common problem with factory manuals, as they were generally loose leaf, so that any revisions, technical bulletins , supplements,etc could be inserted as they became available.
The manual as issued grew and changed from year to year.
So a unrevised version of an 1982 manual might be a lot different to the one issued in 1986.
These revisions, etc, were usually for items which were causing problems in service so the original manual may be light just where it is needed the most, and with the final drive section at least this is the case with this one.