Best gooseneck hitch??
We (meaning my brother the good welder of the family) installed our own.
Using the pattern from a friend who has a welding shop.
Welded a 1"thick 8" wide plate across the frame, over the axle, and trussed it in place with some square tubing.
A hole was drilled in the box where we wanted the ball, which we lined up with the hole we cut in the plate before welding it in place.
Dad has the same pickup I have, 3 weeks older and the 5 speed, long box, but we have identical hitches (go figure). Dad leaves his gooseneck ball in place full time, I unscrew mine when not in use, because of the short box and a perceived need for space.
I put down a rubber mat, and kept the piece I cut out for the ball. It fits in the original hole when the ball is out.
EDIT: forgot to add, my brother welded the nut for the gooseneck ball to the bottom of the plate, which is why I can unscrew the ball when I need to. Just smear it with antisieze before you screw it in.