I'm trying to get together all the information I can for those of us who got the 5th wheel prep option and who don't want to pay $1300 bucks for the Reese/Ford Custom 5th wheel hitch.

If you already have a "Signature Series" Reese or Draw-Tite fifth wheel hitch, you will need a #58419 Service Kit Adapter Foot.
This is from reeseprod.com
"Note: #58419 Service Kit Adapter Foot for Signature Series Fifth Wheels & Goosenecks is Required When Used on 2011 Ford Reese Elite™ Series & OEM Rail Kits"
Hitches - link to quote above
I am assuming the "OEM Rail Kit" refers to Fords 5th wheel prep option.

This is the only place on line I found the #58419 Service Kit Adapter Foot
Fifth Wheel Adapter Kit - Ford OEM Rails to Signature Series Fifth Wheel Reese Fifth Wheel 58419

And if you don't already have the hitch.....
Signature Series Pre-Assembled 18K Fifth Wheel Trailer Hitch by Draw-Tite and Reese Reese Fifth Wheel 40847
or
iqFifthWheelHitches.com - Reese Signature Series Pre-Assembled 18K 5th Wheel Hitch
or
Draw-Tite Signature Series Pre-Assembled 18K 5th Wheel Hitch 40847

I'm also assuming the Reese #30847 and the Draw-Tite #40847 are the same hitch, since they are both made by Cequent.

So....
$123.95 for the #58419 Service Kit Adapter Foot
and
$742.95 for the hitch
--------
866.90 + shipping & handling = you could save $300

Let me know if this is correct or BS, cus' I'm doin' a lot of assumin'.