is a specialty house for repair parts; plumbing and heating. If you can't find a direct replacement in their catalog, do like Ken says and make your own. Sexauer has sheet packing available; catalog #066829 for 1/8" thickness.
Crest/Good is another source for quality repair parts - (800)862-7378
The people that answer the phones at the above phone numbers presume that you know the catalog numbers of what you want; they get real testy when you start asking questions. I give out their phone numbers so that you can ask for the contact information of your local rep. who may be more willing to bird dog the part you need.