QUOTE(914Sixer @ Dec 23 2012, 07:07 PM)
You can use a 911 muffler IF you do not have the stock -6 valance. The -6 muffler was bent at the correct angle for the hole in the rear valance.
Early OE mufflers had the part number (and production date ) stamped into them.
The stamped info is visible at lowest curve of the chamber, nearer the passenger side inlet. Most were Leistritz. The challenge is to find one that is not rusted to illegibility..... or oblivion! Rust free, forty year old muffler ? yeah, no problem.
If you are serious about this and need photos or an example for tailpipe shape/orientation I have perfect examples.