Final-drive and wheel spline wear from skipped lubrication
Shaft-drive Shadows strip their rear-wheel and final-drive splines when the recommended spline lube is skipped — and many owners never do it. Ask for receipts showing spline service at rear-tire changes, and listen for a clunk when rolling on and off the throttle. Caught early it is a cheap grease job; stripped splines mean a new driven flange and possibly a driveshaft.
Ask for repair records covering this item. If it hasn't been addressed and the car is in or near the mileage window, price the $150–$800 repair into your offer — or make it the seller's problem.