Wayne, I have photos of a Wrecker I almost bought. But the photos are on another computer, so I can't get them right away. If you E-mail me by clicking on the envelope above next to my name, that will remind me to go find the photos when I make time some other day. I'm "spent" for the day, or I'd do it now.
I'm assuming you will be mounting a wrecker body on your FC, rather than building one from scratch. I see wrecker bodies for sale once in a while. Ooops, I just read your message again, and you plan to find a wrecker mechanism that fits in your original bed. But I will still send photos of a Holmes wrecker mounted on an FC-170 chassis, with 2 (or 3?) PTO's, including one for the front winch.
I'd like to suggest that you use a Dual Rear Wheel style axle. The beds are heavy, even before you add the weight of a broken down Ford or Chevy.
A four speed would also be desirable because you will need more than one PTO. Plus, that granny gear would make it easier to start-up while towing a heavy load, or on a hill. I have three different trucks with a granny gear, and they are invaluable. (One has a T-98, one is an SM-420, and one is an NP-435. I always have to remember where reverse is, because they are all different. lol.)