Mark,
I'm not sure if the hitch you ordered is a GN hitch, but if it is you can get an adaptor that bolts on to the kingpin on your 5th wheel that will allow you to pull it with your GN hitch. Pop-Up Industries makes one called the RV1. I've been using it for a year now with no problems. I think B&W makes one too. I bought my 5th wheel/GN adaptor from Blue Grass Trailer Sales in Kentucky. They UPS'ed it for $40 and their prices are unbeatable (I couldn't find it cheaper anywhere else). My GN hitches are Pop Up and B&W. No problems with either one of them and they are both rated at 30,000 pounds (both are flip over balls so you do have to crawl in the bed to flip them over, but I wouldn't touch one of those pop up balls - I had one and they are a nightmare to keep clean, lubed, and functional).
Good luck with your hitch setup... ... ... . Bud
Their contact info is:
Lebanon Junction
Distributor
Blue Grass Trailer Sales, Inc.
8860 S. Preston Highway
877-833-3434