Delrin transfer case with several pourpose combining 6 input/output shafts:
1:1 trasnsfer case with or without contrarotating axles shafts
1.31:1 increase trasnsfer case with or without contrarotating axles shafts
1:1.31 decrease transfer case
31% overdrive transfer case with or without contrarotating axles shafts
Very helpful on trucks with axles without different spool gears ratio choise, overdrive transfer more power to front axle, means less turning radius.
Contrarotating axle shafts means less torque twist on side slopes, but you have to turn one axle upside down.