These are helpful for Ford trucks that originally have a shock mount bracket held on by 3 rivets that only accepts a stud style shock. These let you install a common eyelet style shock. 
 
Most higboys don't seem to need these. Most all other applications seem to need these. 

The tan and brown truck in the pictures has part number Bilstein 33-185552 along withSkyjacker FR173S spring, and a 3" lift block and this shock fit well and had good ride quality.
 
You will need to remove the 3 rivets per side, and use included 7/16 bolts to install these to the frame.
 
These are meant for a mounting bolt diameter of 1/2" which is very common

37.5" wide rear frames- These are correct spacing for use with a Super Duty sterling rear axle, 2005+ but that spacing likely works for other axles too. 
 
34" wide rear frames- These will still work for you (assuming you have the oem bracket held by these 3 rivets), but the shocks will NOT align with Sterling 10.5 shock locating pins. You'll need to weld on shock brackets on the axle. 

Many trucks already accept an eyelet style shock in factory form, if that is the case there is no need for you to buy these brackets
 
Includes: 
One pair (2 pieces) upper shock brackets)
7/16 hardware to mount brackets to frame
1/2" bolts and nuts for shocks