I'm contemplating the idea of installing the V8 LE muffler on my 2010 SE. Just comparing both units it appears to be a direct bolt on. The way the piping is going in in both mufflers is oviously different, but the way it lines up with cats is the same on both models. The back piping is the same as far as I can tell. I think going this route will improve flow - V8 mufflers have 2 pipes going in and 1 going out on the back, while 4.0 trucks have 1 pipe going in via a cramped y-pipe. This set up should also be quiet - which is the goal here.
Im currently running custom 2.5 inch y-pipe with 1-in/1out Dynomax VT. This set up is the quietest I could go with with no drone, etc., since Dynomax VT has adjustable valve that opens up fully at WOT and is relatively quiet at mid-throttle, but I think I prefer to keep things stock noise-wise and improve flow where possible. What do you guys think about the idea of running 8V muffler on 4.0? Any potential drawbacks to this set up (aside from wasting more money on parts)?
I think if I was do do this over again to improve flow, I'd go with custom y-pipe to replace the cramped OEM unit and leave the rest of the system stock.

Done! I finally got the parts (ordered 5.6 OEM muffler, crosspipe and a pair of gaskets) and ended up using a muffler only with the other parts going back for refund. My initial theory was that this should be a direct bolt-on project, but I can't still say for sure that it would be the case. The shop ended up leaving the original cross-over pipe in place and modified 5.6 muffler piping to just weld everything on to simplify the process and save money on not using all the parts I have brought it. Here is the result:
Stock SE piping dumps into 5.6 LE piping, black paint covers the welds where the pipes were joined:
These are original 5.6 muffler pipes, but they were cut off at the muffler to be manipulated for better fit and welded back in place. Pipe connecting brace was removed for this reason as well:
On the back side, 5.6 muffler is connected to a stock tailpipe:
Overall i'm finally happy with the result. I think the stock V6 set-up with restrictive y-pipe is not a good set up. V8 muffler eliminates the y-pipe and offers nice flowing 2-in/1-out set-up that improves flow and retains factory stock. I do not hear any change in sound from the new V8 muffler, but the truck feels a little more responsive overall.

Nice find. Hopefully it works like you want it too.