Can you post your model? Use the Advanced Editor link in the upper right of the dialog box you post your reply in.
Also move your post to the General sub-forum. You will get more people looking at the post. Link to move is in the upper right side bar.
It sounds like you need a linear pattern of your angle. Set the spacing to 48" and the instances to however many will fit along the length of your channels. Bear in mind that when choosing the number of instances SW will count your original as 1 so you will need to enter the total number of angles. Also, when setting up the linear pattern, the box for Features to Pattern will probably be on by default. You want to select your angle under "Bodies to Pattern" instead.
Edit: I took a few minutes to create a part to show what I meant. If this isn't what you wanted please explain further.
Part3.SLDPRT.zip 109.3 KB