I just picked up a EZ (98) Jumbo Joe, and realized that the grates are a unique size, so nervously decided to buy some before they go out of stock. Talked to an especially helpful customer service person at Weber today, who was happy to look up all kinds of stuff for me. So I thought I'd share the part numbers if anyone else might need them in the future.
Oh, and she said the official name of the pre-2000 18.5-inch portable grill is the "Jumbo Joe Gold Platinum Tuck-a-Way". Kinda funny bit of trivia.
the top grate is #70605, $10.
the charcoal grate is #7440, $9.99
the legs are still in stock: #86820, $3.85 per leg
the lid lock support is #86821, $3
...all of which got me thinking that a person might be able to build a whole JJ out of parts, hmmm...