Muncie part number 12T38665 is an O-ring used in Muncie CS40 and CS41 Series clutch-shift power take-off units. According to Muncie’s own service parts documentation, this O-ring is listed in the output ratio gear assembly and appears across multiple service part references for the CS40/CS41 family. The CS40/CS41 Series is designed for use with Allison 3000 and 4000 series transmissions, as well as Caterpillar CX transmissions. Keeping the correct O-ring on hand is a routine part of PTO maintenance and rebuild work on these units. Pro Gear and Transmission carries genuine Muncie service parts. Call us to confirm this is the right part for your application.FeaturesGenuine Muncie part number 12T38665O-ring for CS40/CS41 Series clutch-shift PTO unitsReferenced in Muncie service document SP14-03 at the output ratio gear positionAlso appears in Muncie service document SP06-01CS40/CS41 Series PTOs are rated for use with Allison 3000/4000 and Caterpillar CX transmissionsUsed in these Muncie PTO modelsCS40 SeriesCS41 Series