Re: changed transfer case oil, and only took in about 1.5 quarts
The Workshop manual says the transfer case holds 1.5 litres. Not sure what a quart is but using an online converter indicates that 1.5 litres is 1.36 US Dry Quarts or 1.6 US Liquid Quarts so you would seem to be about right.
EDIT: Just checked the US workshhop manual - fill to the bottom of the filler hole - the specified amount is 1.5L, 2.6pts or 1.5 US Quarts. So you have the correct amount.