Cases and internal components are inspected and tested for cracks, stripped threads, shaft warp, gear wear, and chain stretch. Each unit is fully rebuilt with new bearings, seals, and viscous couplers then dyno tested. Zumbrota Transfer Cases are rebuilt to unparalleled standards for confidence and satisfaction driving behind the wheel. Our expert craftsmen take pride in restoring each unit to ensure the utmost quality by diligently executing each step. Cases and internal components are thoroughly inspected and tested for signs of wear such as cracks, stripped threads, shaft straightness, gear wear and chain stretch. Zumbrota uses an exclusive Hydro-blast rinse and blasting procedure on internal and external parts, followed by a proprietary shot-enticed deep cleaning. Each unit is fully rebuilt with replacement of all bearings, seals, and viscous couplers. All finished units are thoroughly spun tested for shift-ability and noise. All transfer cases are shipped in high density plastic totes to eliminate damage in transit.