Mechanical Jack problems of the 2003 Chevrolet Silverado

Vehicle jack is too short to jack up vehicle to change flat tire, jack placed under frame per owners manual. Placing 4inch by 4inch block of wood between ground and jack solves problem - jack is extended as far as it will go. There is no internal threaded screw shaft in jack to extend it. Dealer says there is only one part number for pickup jack, to write "gm" on side of block of wood. Gm says if they get enough complants they'll look into it. . Adding a block of wood under a fully extended jack to remove a flat tire doesn't seem safe as compaired to a jack that is the correct fit for a vehicle. At the price I paid for a new truck I can't understand why gm doesn't provide the correct jack! every Silverado owner who has a flat like I did will get a suprise when they try to change the tire with the provided jack.