[Fweaky]

It's not hard to do. I've done my YJ. The problems are at the frame. If you have a 1" or more body lift The body lift spacer will let the grill clear the brake lines, steering box and frame. If you don't have a body lift you will need to do some trimming on the CJ grill at the bottom. The grill will bolt to the YJ fenders so don't have to swap the fenders if you dont want to.
This link will show you most of what you'll encounter. Turn Your YJ Into A CJ - Jp Magazine

 

[JJs89]

I put the cj fenders on my yj and yes the break lines are the problem that's what I want to know is how it mounts there some idea of how to do it that all I need to be finished