The Eaton Fuller Square Key, part number 19258, is a countershaft assembly component used across a wide range of RTX and RTXF series Fuller transmissions. Illustrated parts lists for 14 models confirm fitment, including the RTX-11610, RTX-12510, RTX-12515, RTX-14610, RTX-14615, RTXF-11610, RTXF-12510, RTXF-12515, and RTXF-14615, among others. Each unit typically calls for two of these keys per countershaft assembly. This key is also referenced in service kits K-1714 and K-1716 where applicable. A genuine Eaton Fuller part sold by Pro Gear and Transmission. Call us to confirm proper fit for your specific transmission model.FeaturesGenuine Eaton Fuller part number 19258Square key for countershaft assembly applicationsFitment confirmed across 14 RTX and RTXF series Fuller transmission modelsTypically installed in pairs (qty 2 per countershaft assembly)Referenced in service kits K-1714 and K-1716 where applicableSold individually by Pro Gear and TransmissionUsed in 14 Eaton Fuller modelsShow all 14 modelsRTX-11610RTX-11615RTX-12510RTX-12515RTX-12610RTX-14610RTX-14615RTXF-11610RTXF-11615RTXF-12510RTXF-12515RTXF-12610RTXF-14610RTXF-14615