I am thinking it takes a Park FR-4. Looks too small for the CT-3 type tool. I have an old Schwinn Approved FW sitting on my desk at work (don't ask why). I work on 495, but a bit west of the the Merrimack. I have both tools and a really big wrench, plus extension.
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Looking for 24T or 21T Dura Ace uniglide cogs FW. Can trade NOS 12T.