I have a early 2004 Dodge 2500 Diesel 6spd 4x4. I jus ordered and Aero4040XL to replace my stock muffler with. I have a completely stock exhaust. Can anyone tell me the stock exhaust size before the muffler? Some say 4" and some say 3.5" and i cant tell exactly since i havent gotten the muffler in so i havent taken my old one out. Also how would anyone recomend to mount the Aero in place? ANy suggestions or info would be greatly appreciated. thanks!