It's the gasket between the turbo and exhaust manifold. That one always blow out on the SR.
It's just a standard 4-bolt turbo exhaust inlet gasket. Just about any vendor will have it. I recommend getting it from here:
http://performancenissanparts.com/ca...oducts_id=1433
Drop the turbo assembly and rebuild it properly. There are a couple of trouble spots if you still have the stock turbo. Try searching a little bit and come back if you can't find anything about it.