Let me see how the tail pipe is attached.
I think it's a standard VW 411 and 412 muffler, I'd ask $300-350 for it on thesamba.
If it's like the one below it's one year only, rare and maybe worth a little bit more to the right person.
BTW The VW 411 and 412 are the original type 4's whose engine ended up in the 914.