The bulkhead fittings that I use are for an agrucultural application. I've got the catalog - from Fleet Supply
in Lewistown (a farm supply store), cost for a 2" was $4.00 or $5.00, which I used for my auto-siphon. I used smaller ones on my GBs - they're inexpensive, they have threads inside so you can thread the pipe, rather than gluing etc. I didn't have leak one!

They're made by
Banjo Corp.
150 Banjo Dr.
Crawfordsville, Indiana 47933
ph765) 362-7367
fax: (800) 458-0232 or (765) 362-0744
sales1@banjocorp.com
http://www.banjocorp.com

Just my 2 centavos ......