The Carvin necks have a brass nut (the Hofners had a zero fret, I believe).
the other obvious difference is that the Hofner necks in '77 and '78 were bolt-on, while the 1979 and later necks were glued-neck and contoured into the body). You can tell the difference the Hofner 860 had only two block inlays above the 12th fret the Carvin neck (and possibly the Hofner 900) has four. In 1979, Carvin had switched over completely to its own necks. The Hofner 900 neck (phased in during the '78 model year) gets narrower at the top. You can tell if it's the Hofner 860 neck if it gets wider at the top and flares out. They later switched to a more LP-like 24.75' neck of their own manufacture. The scale on these guitars, by the way, is 25.25' Carvin was using a Hofner 860 neck for these early models. There will be two rows of eleven pole pieces on each pickup.
In 1978 Carvin switched to the cream-colored M22 series pickups with no covers. Case was rectangular with an orange lining. All CM-140s were set-neck guitars with both body and neck in maple. It will be a stereo guitar with three control knobs, a row of three miniswitches (coil taps and phase switch) and a pickup selector, and it was available in either black or clear-coated maple. The 1977 model will have an ebony fretboard and MOP block inlays. The CM-140 was introduced in 1977 (if it has original pickups with chrome covers with TWO rows of screws, it's a 1977).
