If you have a broken rear axle, neither rear wheel will turn when the prop shaft is rotated, as the diff will ensure that all drive goes to the side with least resistance.
You can easily confirm that the problem is in the rear axle - chock the front wheels, jack up one rear wheel with the handbrake on. If the wheel is free to rotate you have a broken axle or a broken diff (either is possible - the last time I had this it was the diff).
Having established this, you can tell which side axle simply by removing each half axle, which can be done without even jacking it up. If the first test has confirmed the problem is the rear axle, and neither halfshaft is broken, you will have to remove the diff. This is fairly easy to do - with the halfshafts out, disconnect the prop shaft, drain the oil and remove the nuts holding it on. Careful, its heavy! In this case, I predict you will find the shaft carrying the planet gears is broken, and there will be consequent damage. Fortunately, there should be little problem finding a good secondhand diff.
(All these assume that it is a Rover diff - but if it is a salisbury, it is most unlikely to have broken anything, including axles, and almost all 2/2a Landrovers came with Rover diffs front and rear)
Hope this helps,
John

