GM 4L60E Transmission To NP231 21 Spline Transfer Case Adapter 4L60E 2WD and 4WD with removable bellhousing;NP231 21spline transfer case adapters;Adapter length is 3 Advance Adapters Advance Adapters GM 4L60E Transmission To NP231 21 Spline Transfer Case Adapter - 50-0431 50-0431 Transmission Adapters