I appreciate your help, tho.
Ummmmm there is no setting for backlash. If there WAS an official backlash setting a special jig an micrometer would be required. Since the PTO is a very simple and sloppy spur gear. ALSO the input from the transmission is always in the same direction. The rotation is reversed internally (there is a 'reverse' or 'pay out' position). Also the PTOs ARE IDENTICAL IN CONSTRUCTION. There are different part numbers for HIEL vs GAR WOOD, but they are interchangeable (like ordering a WO part for a Ford GPW... same part, different supplier).
The ONLY part manual that specifies HEIL vs Gar Wood parts by specific manufacturer part number is the TM10-1562 on this site
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http://www.tm9-801.com/searchTM10-1562/ ... he/177.pdf
All other SNLs go by the GMC part number.
There are a few SPICER PTOs but only affect a few CCKWs