If you are swapping from a 351M, 400, 351W or 302 to a 460 these will bolt directly to the perches that your truck, or bronco already have. They are for the year range 1974-1982. Additionally, they are built to the correct dimensions to allow you to use the full serpentine system and accessories of a stock EFI 460.
We have had countless customers utilize our 351M swap mounts as a universal motor mount. Why redesign the wheel if these work so well. We include (but do not weld) the perch bolt to give you more flexibility. Bolt them onto the engine then you can build your own frame perches from these out to the frame.