Can I put mufflers at the end of an exhaust system?

[El Campo]

So the truck is lowered 4/6 inches. Only running 3 inch exhaust (is this necessary with a 630 hp 535CI?) if I have to. The problem is that it is a very tight squeeze everywhere for the mufflers. I am thinking that I am going to get the Flowmaster Super 44s. They only have a 13 inch long body and I THINK that I can squeeze them between my Turbo 400 crossmember and the center crossmember. If I cannot however the only other place that I can imagine they would fit is at the very back immediately after the axle. Can you do this??? Oh yes and I definitely definitely want the exhaust all the way out of the back.