also here are the casting #'s....?????....

Main Case

3831704 1963 Only small 6207NR Front Bearing ,Pat. Pending, 7/8" Bore
3839606 1963 - 1964 Regular Bearing Pat. Pending, 7/8" Bore
3851325 1964 -1965 7/8" Bore Patent Pending Mostly 1964
3851325 1964 –1965 7/8" Bore Patent Number
3864848 1965 7/8" Bore Patent Number
3864_____ 1965 Milled off last 3 digits 7/8" Bore Patent Number
3885010 1966 -1967 1" Bore Patent Number
3925660 1968 – 1970 1" Bore Patent Number
3925661 1970 – 1974 (some early 1975 cars) 1" Bore Patent Number


Tailhousing

3831731 1963 "Thin Fin Tail" Driver speedo 27 spline
3846429 1963 "Thin Fin Tail" Driver speedo 27 spline
3846429 1963-1965 Regular thick web, driver speedo, 27 spline
9779246 1964 – 1965 Pontiac Catalina Long Tail Driver Speedo 27 Spline
3857584 1966 – 1970 Passenger side speedo, 27 spline
3978764 1970 – 1974 passenger speedo, 32 spline output


Side Cover

3831707 1963-1965 Early side cover stud type shift shafts
3884685 Cover issued with "584" tail stud type shift shafts
3950306 Short boss with bolt on type shift shafts - no switches
3952642 Long boss bolt on type w/ TCS switch on 3-4
3952648 Short boss bolt on type w/ TCS switch on 3-4

335308 Long boss bolt on type with neutral safety switch. Some have a boss for the switch that is cast but not machined on 1-2.