Currie 9" 3rd Members are 31 spline using a Currie Twin-Trac posi unit for superior performance and durability.9-Plus Sportsman gear case is a 100% new unit cast out of 65,000 p.s.i. nodular iron and features 3.062" carrier bearing bores. Case is complete with caps, cap bolts, billet spanner nuts, and spanner nut retainers.