i just made sure i ran the tank as empty as poss
with a bottle jack i then propped up the tank where the craddle was not touching in to hold the tank,then undid the bolts ,it was a bit of a fiddle as the back bolts if i remember correctly where a pain to reach because of the dif/rear sub, but you can do it
then just fitted back in reverse ,if you check throw by threads (my older ones on my td4,and theres lots of pics on it as i made mine using the old one as a templete)