My Ford F150 FX4 is a grand truck...but has my trailer guy in a bit if a quandry as to how to install my hitch for my gooseneck stock trailer.

We removed the large metal plate and ball from the box, brake box etc from my 2002 F150 with the intention of reinstalling it in my 2004...problem is...the shape of the new frames...they have that raised shape on the side of the enclosed frame and we can't figure how to attach the hitch...I've seen where some guys weld rails to the frame and use them to bolt to, for the drop down ball hitches ( remember, mine is the plate and the ball on my truckbed), but I've been told welding to the frame can affect the warranty on my truck...and, it isn't safe....soooo....any suggestions on how to attach a simple steel bed plate and ball to these new frames??

Thanks...would appreciate any help I can get. )