Ill assume youre talking about the REAR FRAME mounted
receiver hitch (the one under the rear bumper)....
different trailers use different ball sizes...so it might not do any
good for someone to have included or given you one w/ the truck
anyway.
NONE of the trucks came with a ball or mount fromn then factory...
depending on what "class" hitch you have its either a 2" or 2.5" receiver.
make sure you use a PROPERLY rated ball & mount...many
of these "JUNK" ball mounts (available at walmart and pep
boys, etc) are rated considerably less than the hitch can
tow. (typical mounts & balls are rated at 5000lb/500lb
maximums....gross trailer weight/tongue weight)
once you figure out which hitch you have you can order
the mount & appropriate ball (size) on line....
Hitch Solutions The Rapid Hitch
USA-TRAILER-HITCHES.COM - Wholesale Trailer Hitches
Trailer Hitches and Parts for Trailers