The Gen-Y Hitch Shock Absorbing 5th Wheel to Gooseneck Pin Box # GY58GR has dimensions comparable to the Lippert 1621 it is designed to replace. Typically replacement pin boxes like this one keep the same or very similar clearance to the original. It has the same bolt pattern as the Lippert 1621 and mounts using your existing bolts.
I have attached a review video along with a diagram below showing the dimensions of the Gen-Y for your reference. view full answer...