I took a look at the Advance site. The "Warn" overdrive is not the same as the Borg-Warner overdrive. Operation is similar in that it uses a planetary gearset inside a "drum" gear, but all ODs do (even the Laycock-DeNormanville, which is the design that Gear Vendors bought -- they actually purchased AMC's left-over stock and converted those to work as add-on units, then strengthened/improved the design for new manufacture). Other than that there are no similarities. The B-W unit isn't mechanically synchronized as far as I know (I've taken a couple apart -- and put back together in working order). It has an electric solenoid that cuts ignition when engaging to prevent torque application until the planetary is fully engaged (only takes a second or less -- one or two firings missed). The Warn is mechanically shifted, so it needs a synchronizer. The Warn page states a 25% engine speed reduction, all B-W ODs were 30%. Unfortunately there are no parts from the Warn or GV units that will interchange with the B-W. The good thing is that ALL B-W parts, at least post WWI production, will interchange regardless of make. The only differences are possibly the splines on the input gear and the electrical controls. All the OD units have a solenoid and governor, but each manufacturer wired them differently, some with more controls than others. AMC even used 2-3 different wiring schemes, one without a power relay. Studebaker used one of the most complicated (in some models) that I've seen. Check out the B-W manual at http://www.tocmp.com/manuals/trans/Borg-Warner%20Overdrive/index.htm. They also have a collection of Nash and AMC manuals, and info on a lot of various automotive makes and equipment, including a Carter YF manual from 49 and 72, and a cnearly complete AMC 73 TSM (AC is missing, maybe one or two other things, but mostly there). _______________________________________________ AMC-List mailing list AMC-List@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list or go to http://www.amc-list.com