A general guideline for jack points:
Choose a sturdy reinforced part of the unitized car body floorpan. Look
under either side of the vehicle and you will see a boxed section of the
floorpan, running fore-and-aft. This amounts to a "frame" on a frameless
vehicle. You may position the saddle of your floor jack under the leading
end of this "frame" (just behind the front wheel) or under the trailing end
(just ahead of the rear wheel). These are the spots which are used when a
shop technician uses a lift to raise your car. You may use these same
points for jackstands.
The Maxima factory service manual identifies two "garage jack points":
(1) The leading end of the fore-and-aft stamped steel brace which is under
the engine/transaxle in the center of the vehicle. Jacking at this point
raises the entire front of the vehicle.
(2) The center point of the rear axle. Jacking at this point raises the
entire rear of the vehicle.
I replaced the original cup-like steel saddle on my floor jack with a
rubber-faced flat plate (Harbor Freight #36004, $10 +s/h, or equivalent.)
This is kinder to the car, marks it up less. Another approach would be to
fashion a rubber insert for your cup-like saddle. Collect one of those
truck tire treads which litter the highway roadside. Look for a thick one.
Cut out a piece which will fit inside the saddle. Let it "float" or secure
it with a big gob of adhesive, as you wish.
Daniel B. Martin
Nissan owner and D-I-Y mechanic