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enlarged the heck out of the non-drive side image and was able to determine there is a housing stop there so he is all set for a front mech which has a housing stop
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frame's lug pattern is Prugnat 62/d. fork crown is Vagner model DP+.
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as you search for parts you might wish to look also for a dustcap for your Lyotard model Faucheux 15 pedals.
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notice cycle has Universal brake calipers paired with Weinmann brake levers and hangers; no doubt lots of history there!
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all best wishes with it!
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