how can I find out what box I have got on my land rover discovery

Hello I am new to this land rover used to have cars and my last 4x4 was a Pajero :-( sorry but now converted to land rover now I have put a heavy duty clutch kit but I am just wondering what box I have got on as I want to change the oil etc I have got a land rover discovery 3.9 v8 1998 with LPG (if that helps). Thanks

you have an r380 in that case ,can be shown by reverse been behind 5th, atf dexron 2 or 3 or mtf94 you need about 3 litres for gear box and similar amount of ep90 or 80w/90 or 75w/90 for transfer box