Rod of Identification
 

Should be unlimited charges until April 2002 as in never.

https://web.archive.org/web/20020112...html?item=3659

http://www.tski.co.jp/baldio/patch/20020424.html

April 23, 2002 3:00 am

NOTE: We are unable to patch ìcodeî right now because we are in the
middle of making some changes to the basic structure of the game. This
will delay fixes for system bugs and updates (such as Alternate
Advancement Abilities and /commands). Please be patient until we can
get these much-needed changes finished. Because these changes affect
things such as the database that stores player characters, weíre taking
care to make these changes the right way.

Rod of Identification now has 20 charges

Fixed, pending update.

Is this going to fix existing rods, or will we have to vendor recharge them with an unlimited rod?

It will fix all of them.