Just got off the phone from ASV europarts in sydney and he was very helpful.
As stated the manual ratio is 4.1 and the auto 3.64. However, both manual and auto run 4.1 for the front diff. So the ratio in the transfer case must be different in the autos.
Therefore the only way to utilise the 3.64 diff in the manual would be to disconnect the front wheels and have it as RWD.