Actually, trac-loc was only optional on LSC's in '89 and there were no ratio choices...BB = 3.08 open and LSC = 3.27 open (trac-loc optional) I don't believe the 2.73 was used in any Mark VII, only in 5.0 mustangs w/manual transmission. Put in the autolites, FMS wires cost about $50 and you can...