This is for formed steel pieces and plates that gets welded to the front and/or of the engine corssmember to allow the differential to have more upward movement before bottoming out. 

This locates based on the track bar bracket in my 2005+ front end conversion kits- you'll notice the two holes in the track bar bracket align with these two holes in this plate. 
 
The extra clearance is necessary for all F250 and F350 applications where my drop heigth buckets are used with oem coil springs. 
 
This is optional for all F250 and f350 applications where my standard height buckets are used with oem coils. You can still have a decent range of motion and not bottom out under normal driving conditions, but cutting your engine crossmember allows another 3" approximately of travel.

F35C applications do not need the front plate but it can still be helpful- the engine crossmember is already double walled and you can simply cut out part of the inner wall, and what is left is still stronger than other F350 engine crossmembers that are uncut. 

The 2wd front end kits come with a 2 hole spacer that bridges the gap between engine crossmember and track bar bracket. This front weld in piece eliminates the need for that 2 hole spacer. When installing the front piece, first install the track bar bracket. The weld in piece should bolt to the track bar bracket, without any strain on the track bar bracket, and will act as a fixture to hold the front piece for welding. 
 
View the pictures about 1/3 the way down this page for installation ideas- the pictures here were a welded in plate prior to this laser cut and formed piece, but it's the same idea.
 
battlebornbrakes.com/2wd-gallery