Chevy NV4500 4WD Mainshaft It is 19 1/2" OAL and has 32 Splines This NV4500 Mainshaft is for the Chevy 4WD NV4500 Only! You can identify this transmission on a Chevy by cast numbers such as "C-16812" or "C-18157" etc. This transmission has an Iron Case with an Aluminum Top Cover! This Transmission usually comes in the 92-94 Chevy 3/4 Ton or 1 Ton Gas and Diesel Trucks