shown in fig8 the left extension sideboard 4 and the right extension sideboard 5 not shown in fig8 together construct a cargo bed extender package 44 not shown in fig8 but in fig9 the base frame 38 can be bolted tightly to the inner surface of the tailgate through bolt holes 43 a total of 12 holes shown in fig8 the dimension of the base frame 38 is so designed that the extender package 44 can be accommodated between the left sidewall 6 and the right sidewall 7 when the tailgate is in the upright stowed position the mounting of the extender package to the tailgate inner surface constructs a tailgate extension assembly which is similar to what is depicted in fig1 through fig6 and functions similarly in fig9 depicted are a cargo bed extender package 44 bolted to the inner surface of a tailgate 2 both extender package 44 and tailgate 2 are behind the left sidewall 6 and are not seen the cross section a a as specified in fig9 is shown in fig9 a in which depicted are a pivot bracket 45 with a 45 degree pivoting slot 46 welded on each end side of the tailgate 2 a pivot pin 47 installed at the bottom of outward jamb 15 of each sidewall not shown in fig9 a but in fig2 and a rubber liner 48 laid on the cargo bed floor 8 when the tailgate 2 is in its upright position the gravity keeps it at its normal position where the pivot pin 47 is at the right end of the pivoting slot 46 as shown in fig9 a when the tailgate 2 is lowered outward to its flat position the surface of the extender package 44 is initially higher than the surface of.