This is a good gear-driven transfer case to retain when doing an engine or transmission swap. Jeep Dana 300s all use a 23 spline input. Some of the adapters we manufacture include a new Dana 300 input with a different input spline and other adapters retain the stock input. The various Dana 300 input shafts we manufacture include a 10 spline, a stock 23 replacement, a long 23 spline which is .750" longer spline engagement than stock, a 27 spline, a 21, 29, 31, 32, and 35 spline. Therefore, if you obtained a Dana 300 from a salvage yard, please verify the input spline.
The aluminum index retainer incorporates a front seal to protect the transfer case fluid from entering the transmission. The transmission adapter housing normally has a seal that is installed with the open side towards the transmission. This seal can be omitted on transfer case adapter installations, provided a gasket or silicone seal is used in between the adapter and the transfer case. The original Jeep adapters have a small bleed hole that is located between the two seals. This bleed hole is an indicator that one of the seals has gone bad and needs replacing.
Dana Model 300 Transfer Case