FYI CTC... - it's the same "Banana" stock 2.0L muffler for all 73-76 MY's
If you want a new one, then any reseller of JP/Dansk & Porsche dealers sell the current OEM version with a chromed tailpipe (originally you had to buy an optional chrome tailpiece at extra cost back-in-the-day).
Try both Sunset Porsche & Suncoast Porsche online parts websites for the best dealer pricing for the new OEM Dansk ones, & look for sales at Sierra Madre (they have 914 parts sale on now IIRC), AutoAtlanta, etc., plus Google search for them to price check.
Folks on here occasionally sell nice used ones, so look in the Classifieds there, & on 914club, TheSamba, etc.
Good Luck!
Tom
///////