We are not using an integrated shifter. If you do that, you are just gonna have another tremec that doesn't fit. It isn't a stock shifter because it is 5 speeds. It is stock arrangement. The shifter and linkage will be part of the package when the transmission is purchased. We are making a 4.35" bearing retainer and a 4.80" bearing retainer. Sorry, no 5.125 OD size. Just not enough call for one. We have an adapter ring available for the 5.125" application though.