The service bulletin refers to the seals at the end of the hydroistat pump shafts getting hard and leaking when exposed to heat over time. The seal which is currently available is the replacement for the original style seal.......This was not so much of a problem on the medium and small frame loader like your 665. The problem was much more prevelent on the 885 and 865s.Messick's has the repair kit to comply with this AD, appears to involve one of the hydraulic pumps.