I want to put a new 2.5" exhaust system on my 1967 GTO. I want to use stainless steel. Flow master has a SS system with H-pipe (preferred over X-pipe) but they differentiate between 64-67 and 68-72 model years. I know they say the 64-67 exits behind the rear wheels and 68-72 exits rear, under bumper. I want exit rear, under bumper. Some mail order firms just sell the one kit for 64-72 with rear exit, like I want, but only aluminized steel and I want stainless. My question (finally) is, from the trans crossmember back, is there any other difference in exhaust configuration than exit point, or can I put the "68-72" kit with rear exit on my 67 without any trouble?