http://www.gmpartswiki.com/getpage?pageid=62578
In another parts book
Group 9.750 HEAD, TACHOMETER
3852111@ 1966/ALL CHEV W/250 or 292
3839947@ 1966/ALL CHEV W/V-8
@ NEW PARTS MASTER CATALOG
3828689* 1963 w/V-8
* NEW PARTS INITIAL CATALOG
In another parts book
3771216 1961-62 W/V-8
TRANSMITTER/ TACHOMETER
2339638 1961-62 W/V-8