Diffs for 1988 H J 75 ute

Hi one and all This is a great site , dont you just love it . Now the problem is just a little one without taking the diff out of my hj75 how do you know what it is , does this makes sense Ill start again the diff is nakkerd in the ute and have been givern one out of a sixty series station wagon how do I tell if it is the same , dont want to take the old one out then have to put it back. There that will do can anyone help . I am only a pensioner and could do without the exercise .Thanks in advance for you'r help , Cheers Catchy snr