does anyone know amything about regearing or adding and additonal overdrive unit to a 47RE, im working on a project with a mildly built Cummins ISB and would really like to have 5 gears and would have a woody if i could get six, i looked into using an allison but i don't have $9,000 to blow on a new tranny, i know from my '96 4x4 ram its about 2250 rpm around 75-80 mph with 3.73 gears which is were i run on the interstate, i'd like to run 4.10 gears and drop my rpms down to 2000 or below at that same speed, i realize im asking for alot, but im curious if anyone has doen soemthign simalar