Rocky,
I'm going to probably go with these guys, Carb unlimited. They are close to me so I can corner them if there is an issue. I have not yet delt with them.
Weber 48 IDA Parts Page (carburetion.com)
There is also these guys, not sure on them. Sounds like they are decent from other user groups.
REDLINE - Serving the U.S., Canada, Central and South America for over 30 years (redlineweber.com)
Haydude