New to 5th wheel. Question on slider/pin for crew cab.

With that short of bed the sidewinder is the best option. You would also want a light wt hitch in the truck, due to the limited payload capacity. Auto-sliding hitches are heavy, and work best in 6.5' bed.

You don't say what the FW weight is, or the loaded pin wt, but be sure your truck is up to the task before proceeding. Be aware of payload and RAWR.

Jerry