rtmjr13@optonline.net wrote:

Hello all, Robby 13 here. New project! Going to install the stock factory transverse system on both cars- 68 289 coupe, and 67 390 gt. I had been toying with the idea for a while now, I just got home from a large car show at Belmont Racetrack in N.Y.- long island. I saw and heard 2 cars, a 67 gt 500, and a 68 289. I forgot how nice n mellow they sounded. The question is on the transverse muffler, which way is the seam situated, bottom or top, and what probably dictates that is how it is situated and configured inside the muffler. Any ideas? They have full kits available, from the H pipe all the way back , and it comes in 2 diameters, 2" and 2.25". Any ideas, thoughts etc? It is true , the older you get, the quieter you want. When I first bought the cat in 74, I ran Hooker headers, and hush thrush connected directly to the headers - and that's it! Nothing from the muffler back! Can you imagine? Well, I was in my 20's, now I'm 60- nuff said.

Hmmmm? I am in my 60's and just went the other way.  I yanked out my soul-less single pipe transverse muffler and installed duals.  As far as I am concerned, that 289, even with a 2bbl, loves dual 2 1/4 pipes.
 

R-13, if you are going back in with a factory stock or factory type exhaust system, it will only fit one way.  Assuming you are using the stock hangers. 
Enjoy