This is a Brand New 4wd 29 Spline Updated Mainshaft for the Dodge Diesel NV4500 Transmission it will only work for the Dodge. You can identify this transmission in a Chevy by cast # "C-16812" or "C-18157" and in a Dodge by "C-18157" or "C23167" This transmission has an iron case with an aluminum top cover! This transmission usually comes in the 1990-95 Chevy and Dodge 3/4 ton or 1 ton gas and diesel trucks. Note: If you have a Chevy NV4500 and need a mainshaft we do have those available too please see our store.