You need to inspect your lead candidate car(s) thoroughly to decide on purchase and price. Tick the appropriate box for each check and total the points. Be realistic where bodywork is concerned and vigilant for V12 engine faults.

Overall stance
If the car has self-levelling suspension, ask that it be left overnight before you arrive, to see if the rear rises slightly on start-up. Once running (or at any time if no SLS is fitted) an XJ40 should sit flat and level front to back and side to side, or very slightly higher at the rear, especially with low fuel load (check the gauge). The heavy V12 can sag at the front also, and thus be level, but low. Note that cars with SportsPack suspension or low-profile tyres on standard wheels will sit lower.
On level ground the bottom of the front subframe should be about 160mm above ground with 215 width tyres and 155mm with 205s. An easier but less precise method is to measure from the top of the wheelarch through the centre of the wheel to the ground. Unladen with half a tank of petrol, a normal car will sit around 660-665mm high at this point, and again, level or slightly higher at the rear.

Body panels
A good XJ40 should have undistorted panels with even shut lines and the doors following the body contours not sticking out at the base. Look for filler bulges along the bottom of doors or wings and around the headlamps, arches and sills. Feel the wheelarch returns for rough metal or double thickness or seams from repairs, especially at the lower front area of the rear sills. Loose or missing mud shields in the front wheelarch can hide rot, so clean and inspect by torchlight. The area around the filler flap can suffer badly and the radiator support crossmember is an inspection fail if unsound, but may not be visible with the undertray in place.
Underside and sills
The front footwell corners around the jacking points rust easily, where stone chips allow water behind the underseal. Check from inside and outside the car and try to lift the car on the jack to check for creaking/buckling if possible. Beware of thick underseal, over poor welding or bad steel. The inner sill floor seam rusts in a neat line, compromising shell strength significantly. A-frame attachment points are normally not too bad but the rear lower quarters can be, although they are not structural. Check for rust in the chassis rails within about a foot any front or rear suspension mount and if the front or rear screen bases are perforated then walk away, as the water will have rotted inside the lower chassis angles too. The front upper section of the sills is hidden behind the wings but water and mud can collect here behind the splash panel and rot down from above.