I think those TB gaskets can be reused a few times as long as it doesn't tear when you remove the TB. I had mine apart the other day while replacing the IMRC box and I just put the old one back on. I was careful taking it off, it didn't appear to be damaged and so I just reused the old one when it was time to reassemble everything. No local dealer in the St. Louis area had one in stock anyway.
I'd put a new one on about 11 months ago so if yours has been on there for a few years you might have problems with it tearing when you pull it off.
