Modifying Dumb Solids with Multiple Solidbodies

I downloaded a 3D model from a suppliers website and the length

of the rail I have modified by adding a cut to the one solidbody to get

it to the length we need it at.  Problem is as you will see when you open up my

part is the end cap is now detached.  This is a 2 part question.  First is the cut the

best method to shorten this or is there a better solution?  I need the rail shortened

with the end cap butted up to the rail.  Second if the cut is the way to go how do I

get the end rail to butt up to the rail?

I already tried using feature works and it didn't work properly.

Thanks for your help.

SolidworksParts And Features