161K needs tires Crank Sensor Pick up Plate + Trade or Fix?

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Jeep died - towed to Dealer. Says must replace Crank Sensor and Pick Up Plate on Dist $564.10 before they can find out what else may be wrong with it...I have very little $$ but do not want to put good into more bad. Fixing cheaper than a car payment....but what else will go wrong? Transmission? more electrical? Help..single and 53.