It does go directly from under the rear of the cab to the front of the bed.
I also believe that if it has about 9/16" holes at either side, it is placed so that the front pair of bed mounting bolts go thru those holes as well.
The longer 'leg' of the "L" shaped panel goes horizontal and will be positioned so that about 1" of it is under the character line edge of the rear of the cab. The shorter leg goes at the rear and is placed in the upward postion.
In the left/right center of the forward edge of this dust shield there is supposed to be an 'anti-rattler'. I do not recall the starting date for the narrow bed, but for the first 90 days, this anti-rattler was a stack of 1/16" thick pieces of 'rubber' that were about 3/4" x 1". From that point on it became a 1/4" thick one piece anti-rattler. In both cases there was a 9/32" hole in the center for a tubular rivit.
If any of this needs to be more specific, I will be happy to get out my notes and clear up any issues if it would be of any help to you.
I like Pick Ups.