You can supposedly, source the exact RFID chip alone.... but you are far better off buying a new fob (do not buy a previously used/programmed one) and have it programmed in regard to your JT. Yes, you can have more then two fobs programmed to a JT. I myself have 4.
FYI: Some guy's / gals...
Yes, contrary to a post by the forum member earlier in this thread, the RFID chip alone does not behave as mentioned in that post.
When you walk up to your JL, to unlock/lock, ... to see the JT interact with you and your fob, you have to have a circuit board with a serviceable fob battery...
Indeed, your buttonless factory JT fob, as well as all JT factory fobs, does have a fob battery.
We explained a bit here:
https://www.jlwranglerforums.com/forum/threads/🪛-fob-101-know-thy-jl-key-fob🪛.88719/post-1855159
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