I may have a 13" but. That's too long
Blue Ox can make one any size you need.
BUT WARNING.. A drop hitch places a TORQUE load on your receiver and the cross arm it is welded to.. This can rip it right off the frame rails. So inspect the ends of the cross bar the cross bar and the hitch often LIke every time you tow.
How do I know this.. The hard way of course. the company that rebuilt mine (Simpson and Sons' Servie in Indiana as I recall. S.E. of I think Batesville. (Along that highway) next door to an RV dealer. about All I can recall today)
Well. let' just say the job they did makes the job the factory did look like a joke. They WAY over built those brackets.