jack it up on the diff, and put jack stands under the rear to not get inthe way of the tank coming down.
open fuel pump access in trunk... unclamp fuel/return lines.
unbolt the gas fill tube (from gas door), i forget how many spots its attached, make sure its free to come down with tank.
there are 2 big metal straps holding it in... unblot the front side and the belts hinge on the rear mount spots.... so they will easily come down and release the tank down. make sure you have some way to nicely lower it if its full of fuel, shit is HEAVY.
putting one back in is harder than out... just make sure nothing is still holding it up besides the belts before you remove those, its a pain to get other stuff off while holding tank in place...
**estie says about subframe, ive never done s14 so listen to that. i only have done s13. with subframe coming out, put the jack stands in front of rear wheels a little? on frame rails i guess?