have you thought about fabricating your own? the exhaust on my 1950 is pretty simple and i don't imagine that the 53's were all that different.

you could spend roughly the same amount or less on straight tubing and a tube bender and make your own, with the added benefit of having a tube bender for some future project(s). harbor freight has some inexpensive tube benders that would work very well for fabricating an exhaust system and then you have the added benefit of bragging rights that you built it yourself!

if you need dimensions (i.e. bend card) for a 3600, i could take some measurements off of mine or someone else who has a 53 3600 could certainly help you out if you wanted to make your own.

just a thought...