I just had my wheels swapped front to rear because i thought it would be a good idea, a garage near me did it for nowt but i was shocked to see that they placed the jack under the rear diff, is it safe to do this? i did not like to say anything at the time as they were doing me a favour.

I jack mine up on the rear diff, so does my mechanic. Apparently causes no problems.
Tim

Should cause no problems, i jack mine on the diff, but put a piece of wood on the jack to stop metal/metal contact.