Before you all yell and claim NOOB....I did in fact search for this. But nothing is clear on the muffler and such and I even found most saying it's the easiest muffler to get on there and another saying it's a lot of work.

I might be in the process of buying an 04 dyna Muffler for my 03.

If I was to buy this, it came right off a HD: what would I need to do to get it on? Weld something? how about brackets and or clamps?

Thanks for the clarification.

thank you for you're explanation.

Looks like I wont get that now. I can't afford to re-jet right now. I will look up the white spacer mod and idle screw and do those 1st and when I get some extra cash fore re-jetting, i'll get that as well as any mufflers that are currently being sold.

Yea, I was looking to get one of them, but isn't that harder to install on the bike?

tell you what...how about someone SELL me their muffler they had on ther bike  

Thats what I was thinking...just go to a muffler shop and have them make me one and i could prob polish it if it isn't already.

You want one with no crossover tube...looks like a little one inch tap at the exhaust pipe end.  
Also people say that the rail type mount is an easier swap than the tab type mount, but either will work.  Check e-bay pics and you'll spot the difference.  Sellers often have no idea what they came off of...

Sorry DJ,  I don't know numbers...if you can post a pic?
Basically you can make any HD muffler fit, some take a little more effort.
No crossover tube at the front, and you don't have to plug it.  Rail mounts are rumored to bolt right up to the hanger bracket, tab mounts you may need to drill a new mount hole in the bracket.  Some folks have added a bit of pipe to angle the muffler out away from the brake lever, I didn't.  
Connecting the muff to the pipe will require either cutting a bunch of extra slots in the muffer end to let you clamp it down (I did), or using strips of tin can to build up the diameter of the pipe.  I also shaved down the factory gasket to help fill the space.  Or figure something else,... the point is the muffler I.D. is a bit bigger than the pipe O.D.
It's all just a matter of riggin'.  It's all possible and the challenge is great fun.  Share your ideas when you're done and if you can show pics, better yet...

Here's a pic of mine, I used a piece of chrome muffler pipe end from AutoZone to cover the clamp joint.

Can't tell much...I don't see a crossover in the pic but it could be on the other side...  I wouldn't pay over $30.00 for the pair.  I got a pair for $25.00.

FYI,...Here's a pic of a pair of sportster mufflers that you don't want.  They have the crossover tube that is a hassle to block and kid of ugly.  See it?  Up at the inlet end.
On the other hand they have the rail mount (the 2 bolt mounts) instead of the single tab mount.  That's good but not necessary.
Grabbed this pic from e-bay so it will disappear in a couple of days.