8511 is an odd one, very little mention of it in Clausing catalogs beyond occasionally seeing the model number listed. Unclear to me whether it was just an 8520 mill sold without the head, buyer to supply own or actually sold with a Bridgeport M head installed.
Hmm I've found a listing for an 8511 on the Bangor ME CL, and that is definitely a standard 8520 / 25 head on there, not a Bridgeport M head. Either someone converted it back to 8520 spec or 8511 was sold as a headless mill, and then someone installed an 8520 head on it turning it into an 8520 despite what the badge says. Clausing did sell the heads alone (8628 with MT2, 8629 with BS7) or the complete turret assembly (8638 / 8639). Interesting that the seller says the only difference between 8511 and 8520 is only having one crank on the left side of the table instead of one on both ends. Every other 8511 I've seen had a Bridgeport head, but this furthers my thought that 8511 was just a headless mill. Maybe only sold with one crank to keep costs down as I don't see them redesigning the table for a weird one off model.
https://maine.craigslist.org/tls/d/bangor-clausing-8511-miller/7481981845.html
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