What is the correct exit location for exhaust on a 68SS? Is it behind the rear wheels with a downward pitch ... or is it out the back with chrome tips like a 69? Or was there an option for both? Currently mine has 2.5 inch pipes off of the minifolds to the mufflers, then 2 inch cobbled up looking tailpipes with the behind the rear wheels turn down. I am going to have the tailpipes done again and prefer the look of the rear exit with chrome tips .. but want to do whatever is correct. Thanks.

No chrome tips out the back for 68. They turn down and out behind the rear wheels, as you mentioned.