All you have to do is remove all the existing suspension. Have some spacer plates made, should be about 1/2 inch per side. Measure, measure, measure. You will have to also space the steering box, line up your centerline and bolt the saddle to your frame the same way it unbolted from the donor frame. Once you have bolted everything up recheck all your bolts, I used grade 8 bolts. I also had previously added a 350 to my truck so I had motor mounts already welded to the frame. I think, not sure, that you can use the mounts that are on the saddle, this will however put your engine extremely low in the truck. I wouldn't suggest it. Anyway, if I get a chance and anyone is truly interested I can take some pics of my application. Any other questions just let me know and I will happily share my experience.
I found a website that has reposted the original magazine article that I found the idea from 5 years ago. It is
http://home.cinci.rr.com/jeffreytom/pg4a.html
Just so you know, there are many detractors to this setup. I myself love it, it was inexpensive and it works. I owned a mustange II and I wouldn't want to have the brakes on that car trying to stop my truck. Just a personal opinion.