Kohler K91 Owner's Manual page 208

FOREWORD
This service and repair manual has been compiled to provide
authorized Wheel Horse service personnel with the proper procedures
and techniques for servicing Wheel Horse automatic transmissions.
The following index lists all areas covered. It is advisable to read
all of the introductory sections first to gain a proper understanding of
the Wheel Horse automatic transmission.
The automatic transmission is a sophisticated piece of machinery.
Maintain strict cleanliness control during all stages of service and
repair. Even a small amount of dirt or other contamination can severely
damage the system.
Although this manual deals primarily with the Sundstrand piston-
piston type hydrostatic transmission, service and repair procedures for
the older hydrogear type transmission have been included in a separate
section